I am not certain, but my intuition is that the issue should be fixed
somewhere around here.

An alternative could be to set the arrow position not when receiving a
message, but when the chat buffer is not being displayed anymore.  One
edge case I foresee is to handle the situation when no new messages were
received, and the buffer was just selected manually.

> In GNU Emacs 29.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version 3.24.33, cairo version 1.17.6)
>  of 2022-04-09 built on T480s
> Repository revision: 8b3748c234e8be8c2b34c263cb216fef5a5f2279
> Repository branch: master
> System Description: Arch Linux
>
> Configured using:
>  'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
>  --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
>  --with-sound=alsa --with-modules --without-libotf --without-m17n-flt
>  --without-gconf --without-gsettings --with-native-compilation
>  --with-xinput2 --with-pgtk --without-xaw3d --with-sound=no
>  --without-gpm --without-compress-install
>  '--program-transform-name=s/\([ec]tags\)/\1.emacs/'
>  'CFLAGS=-march=native -O2 -pipe -fno-plt -fexceptions
>  -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security
>  -fstack-clash-protection -fcf-protection -g
>  -ffile-prefix-map=/home/davide/src/emacs-git/src=/usr/src/debug'
>  LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'
>
> Configured features:
> ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS HARFBUZZ JPEG JSON LCMS2
> LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PGTK PNG
> RSVG SECCOMP SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP XIM GTK3 ZLIB
>
> Important settings:
>   value of $LC_MONETARY: it_IT.UTF-8
>   value of $LANG: en_GB.UTF-8
>   locale-coding-system: utf-8-unix
>
> Major mode: Lisp Interaction
>
> Minor modes in effect:
>   global-git-commit-mode: t
>   magit-auto-revert-mode: t
>   shell-dirtrack-mode: t
>   rcirc-track-minor-mode: t
>   global-tree-sitter-mode: t
>   dired-hist-mode: t
>   electric-pair-mode: t
>   recentf-mode: t
>   save-place-mode: t
>   global-diff-hl-mode: t
>   yas-global-mode: t
>   yas-minor-mode: t
>   which-key-mode: t
>   global-auto-revert-mode: t
>   repeat-mode: t
>   pixel-scroll-precision-mode: t
>   undo-hl-mode: t
>   display-line-numbers-mode: t
>   display-fill-column-indicator-mode: t
>   flymake-mode: t
>   rainbow-delimiters-mode: t
>   highlight-parentheses-mode: t
>   corfu-global-mode: t
>   corfu-mode: t
>   marginalia-mode: t
>   savehist-mode: t
>   vertico-mouse-mode: t
>   vertico-mode: t
>   minibuffer-depth-indicate-mode: t
>   global-so-long-mode: t
>   override-global-mode: t
>   tooltip-mode: t
>   global-eldoc-mode: t
>   eldoc-mode: t
>   show-paren-mode: t
>   electric-indent-mode: t
>   mouse-wheel-mode: t
>   tab-bar-mode: t
>   file-name-shadow-mode: t
>   context-menu-mode: t
>   global-font-lock-mode: t
>   font-lock-mode: t
>   size-indication-mode: t
>   column-number-mode: t
>   line-number-mode: t
>   transient-mark-mode: t
>   auto-composition-mode: t
>   auto-encryption-mode: t
>   auto-compression-mode: t
>
> Load-path shadows:
> ~/src/undo-hl/undo-hl hides /home/davide/.emacs.d/elpa/undo-hl-1.0/undo-hl
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-draft hides /usr/share/emacs/site-lisp/notmuch-draft
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-compat hides /usr/share/emacs/site-lisp/notmuch-compat
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-jump hides /usr/share/emacs/site-lisp/notmuch-jump
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-mua hides /usr/share/emacs/site-lisp/notmuch-mua
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-message hides /usr/share/emacs/site-lisp/notmuch-message
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-tag hides /usr/share/emacs/site-lisp/notmuch-tag
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-query hides /usr/share/emacs/site-lisp/notmuch-query
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-print hides /usr/share/emacs/site-lisp/notmuch-print
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-maildir-fcc hides /usr/share/emacs/site-lisp/notmuch-maildir-fcc
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-address hides /usr/share/emacs/site-lisp/notmuch-address
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-parser hides /usr/share/emacs/site-lisp/notmuch-parser
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-show hides /usr/share/emacs/site-lisp/notmuch-show
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-wash hides /usr/share/emacs/site-lisp/notmuch-wash
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-hello hides /usr/share/emacs/site-lisp/notmuch-hello
> /home/davide/.emacs.d/elpa/notmuch-0.35/coolj hides /usr/share/emacs/site-lisp/coolj
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-lib hides /usr/share/emacs/site-lisp/notmuch-lib
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-tree hides /usr/share/emacs/site-lisp/notmuch-tree
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch hides /usr/share/emacs/site-lisp/notmuch
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-company hides /usr/share/emacs/site-lisp/notmuch-company
> /home/davide/.emacs.d/elpa/notmuch-0.35/notmuch-crypto hides /usr/share/emacs/site-lisp/notmuch-crypto
> /home/davide/.emacs.d/elpa/transient-20220406.1156/transient hides /usr/share/emacs/29.0.50/lisp/transient
>
> Features:
> (shadow sort company-oddmuse company-keywords company-etags
> company-gtags company-dabbrev-code company-dabbrev company-files
> company-clang company-capf company-cmake company-semantic
> company-template company-bbdb mail-extr emacsbug ox-odt rng-loc rng-uri
> rng-parse rng-match rng-dt rng-util rng-pttrn nxml-parse nxml-ns
> nxml-enc xmltok nxml-util ox-latex ox-icalendar org-agenda org-refile
> ox-html table ox-ascii ox-publish ox scroll-lock expand-region
> text-mode-expansions cc-mode-expansions the-org-mode-expansions
> python-el-fgallina-expansions er-basic-expansions expand-region-core
> expand-region-custom rainbow-mode xterm-color conf-mode flymake-cc
> consult-icomplete icomplete diff-hl-dired matlab-cgen tempo
> consult-imenu tabify man cus-edit cus-start cus-load etags fileloop
> notmuch notmuch-tree notmuch-jump notmuch-hello notmuch-show
> notmuch-print notmuch-crypto notmuch-mua notmuch-message notmuch-draft
> notmuch-maildir-fcc notmuch-address notmuch-company notmuch-parser
> notmuch-wash coolj notmuch-query icalendar diary-lib diary-loaddefs
> notmuch-tag notmuch-lib notmuch-version notmuch-compat debug
> consult-xref grep xref cl-print timer-list novice helpful trace edebug
> backtrace info-look f elisp-refs help-fns misearch multi-isearch ibuffer
> ibuffer-loaddefs goto-addr bug-reference autoload radix-tree mm-archive
> face-remap magit-extras magit-bookmark magit-submodule magit-obsolete
> magit-blame magit-stash magit-reflog magit-bisect magit-push magit-pull
> magit-fetch magit-clone magit-remote magit-commit magit-sequence
> magit-notes magit-worktree magit-tag magit-merge magit-branch
> magit-reset magit-files magit-refs magit-status magit magit-repos
> magit-apply magit-wip magit-log which-func imenu magit-diff smerge-mode
> diff git-commit log-edit add-log magit-core magit-autorevert
> magit-margin magit-transient magit-process with-editor magit-mode
> transient magit-git magit-base magit-section crm url-http url-gw
> url-cache url-auth hl-line cdlatex texmathp org-indent image-file
> image-converter org-element ol-eww eww xdg mm-url ol-rmail ol-mhe ol-irc
> ol-info ol-gnus nnselect gnus-art mm-uu mml2015 mm-view mml-smime smime
> dig gnus-sum gnus-group gnus-undo gnus-start gnus-dbus dbus gnus-cloud
> nnimap nnmail mail-source utf7 netrc nnoo gnus-spec gnus-int gnus-range
> gnus-win gnus nnheader range ol-docview doc-view jka-compr image-mode
> exif ol-bibtex ol-bbdb ol-w3m ol-doi org-link-doi org-mouse elfeed-org s
> dash ob-shell shell ob-python python ob-gnuplot ob-ditaa ob-C cc-mode
> cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars
> cc-defs org ob ob-tangle ob-ref ob-lob ob-table ob-exp org-macro
> org-footnote org-src ob-comint org-pcomplete pcomplete org-list
> org-faces org-entities noutline outline org-version ob-emacs-lisp
> ob-core ob-eval org-table oc-basic bibtex ol org-keys oc org-compat
> advice org-macs org-loaddefs format-spec find-func cal-menu calendar
> cal-loaddefs elfeed-show elfeed-search message sendmail yank-media
> rfc822 mml mml-sec gnus-util mm-decode mm-bodies mm-encode mail-parse
> rfc2231 rfc2047 rfc2045 mm-util ietf-drums mail-prsvr mailabbrev
> mail-utils gmm-utils mailheader shr pixel-fill kinsoku svg dom
> elfeed-csv elfeed elfeed-curl elfeed-log elfeed-db elfeed-lib avl-tree
> generator url-queue url-file url-dired xml-query xml rcirc-menu
> hippie-exp company-yasnippet vc-mtn vc-hg vc-bzr vc-src vc-sccs vc-svn
> vc-cvs vc-rcs vc-git matlab matlab-scan matlab-syntax matlab-compat
> embark-consult consult-vertico consult disp-table gnutls network-stream
> puny nsm rmc rcirc-color rcirc epa-file epa derived epg rfc6068
> epg-config parse-time iso8601 vertico-directory char-fold mule-util
> cursor-sensor vertico-repeat tree-sitter-langs tree-sitter-langs-build
> tar-mode arc-mode archive-mode tree-sitter-hl tree-sitter
> tree-sitter-load tree-sitter-cli tsc tsc-dyn tsc-dyn-get dired-aux
> dired-hist dired-x dired dired-loaddefs tsc-obsolete elec-pair embark
> ffap ace-link avy recentf tree-widget wid-edit saveplace-pdf-view
> bookmark pp saveplace company auth-source-pass diff-hl log-view
> pcvs-util vc-dir ewoc vc vc-dispatcher diff-mode yasnippet-snippets
> yasnippet which-key autorevert filenotify repeat pixel-scroll cua-base
> undo-hl pulse color iedit iedit-lib server display-line-numbers
> display-fill-column-indicator time-date checkdoc lisp-mnt flymake-proc
> flymake project compile text-property-search comint ansi-color ring
> thingatpt rainbow-delimiters highlight-parentheses delight finder-inf
> cape corfu marginalia savehist orderless vertico-mouse vertico edmacro
> kmacro modus-vivendi-theme modus-operandi-theme modus-themes
> no-littering comp comp-cstr warnings rx cl-extra help-mode mb-depth
> so-long use-package use-package-ensure use-package-delight
> use-package-diminish use-package-bind-key bind-key easy-mmode
> use-package-core tex-site info package browse-url url url-proxy
> url-privacy url-expand url-methods url-history url-cookie url-domsuf
> url-util mailcap url-handlers url-parse auth-source cl-seq eieio
> eieio-core cl-macs eieio-loaddefs password-cache json map url-vars seq
> gv subr-x byte-opt bytecomp byte-compile cconv cl-loaddefs cl-lib pcase
> iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
> lisp-float-type elisp-mode mwheel term/pgtk-win pgtk-win term/common-win
> tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
> newcomment text-mode lisp-mode prog-mode register page tab-bar menu-bar
> rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
> font-lock syntax font-core term/tty-colors frame minibuffer nadvice
> simple cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan
> thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian
> slovak czech european ethiopic indian cyrillic chinese composite
> emoji-zwj charscript charprop case-table epa-hook jka-cmpr-hook help
> abbrev obarray oclosure cl-preloaded button loaddefs faces cus-face
> macroexp files window text-properties overlay sha1 md5 base64 format env
> code-pages mule custom widget keymap hashtable-print-readable backquote
> threads dbusbind inotify dynamic-setting font-render-setting cairo gtk
> pgtk lcms2 multi-tty make-network-process native-compile emacs)
>
> Memory information:
> ((conses 16 2989949 527679)
>  (symbols 48 58328 5)
>  (strings 32 529101 94588)
>  (string-bytes 1 32670177)
>  (vectors 16 151986)
>  (vector-slots 8 3099296 315632)
>  (floats 8 4276 12424)
>  (intervals 56 283208 88)
>  (buffers 992 81))
>
>
>
>

-- 
	Philip Kaludercic