Hi,

I constated that using the read syntaxe ?\"
will interfere with any prettified symbols below it in the buffer.

To reproduce :
(setq-default prettify-symbols-alist '(("lambda" . 955)))
(prettify-symbols-mode 0)
(prettify-symbols-mode 1)
lambda
?\"
lambda


In GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.5)
 of 2019-09-23, modified by Debian built on x86-grnet-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description:	Debian GNU/Linux 10 (buster)

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --enable-libsystemd --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --build
 x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --enable-libsystemd
 --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --with-x=yes
 --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
 -fdebug-prefix-map=/build/emacs-StqULU/emacs-26.1+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 THREADS LIBSYSTEMD LCMS2

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8

Major mode: mu4e:main

Minor modes in effect:
  ivy-posframe-mode: t
  desktop-save-mode: t
  global-auto-revert-mode: t
  company-prescient-mode: t
  electric-pair-mode: t
  yas-global-mode: t
  save-place-mode: t
  savehist-mode: t
  shell-dirtrack-mode: t
  recentf-mode: t
  dired-async-mode: t
  ivy-rich-mode: t
  ivy-prescient-mode: t
  ivy-mode: t
  delete-selection-mode: t
  projectile-mode: t
  prescient-persist-mode: t
  override-global-mode: t
  show-paren-mode: t
  global-hl-line-mode: t
  display-time-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  global-prettify-symbols-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  overwrite-mode: overwrite-mode-binary

Load-path shadows:
/home/user/.emacs.d/elpa/map-2.1/map hides /usr/share/emacs/26.1/lisp/emacs-lisp/map
/home/user/.emacs.d/elpa/nadvice-0.3/nadvice hides /usr/share/emacs/26.1/lisp/emacs-lisp/nadvice
/home/user/.emacs.d/elpa/let-alist-1.0.6/let-alist hides /usr/share/emacs/26.1/lisp/emacs-lisp/let-alist

Features:
(shadow flyspell ispell face-remap emacsbug whitespace
elfeed-goodies-logging elfeed-goodies-new-entry-hooks mm-url gnus
nnheader elfeed-goodies-split-pane popwin elfeed-goodies-show-mode
ace-jump-mode noflet cl-indent elfeed-goodies-search-mode elfeed-goodies
elfeed-org elfeed-show elfeed-search bookmark shr svg dom elfeed-csv
elfeed elfeed-curl url url-proxy url-privacy url-expand url-methods
url-history url-cookie url-domsuf elfeed-log elfeed-db elfeed-lib
url-util url-queue xml-query xml epa-file org-mu4e mu4e mu4e-speedbar
speedbar sb-image ezimage dframe mu4e-main mu4e-view mu4e-headers
mu4e-compose mu4e-context mu4e-draft mu4e-actions org-capture ido
rfc2368 mu4e-mark mu4e-message flow-fill html2text mu4e-proc mu4e-utils
doc-view jka-compr image-mode mu4e-lists mu4e-vars message rmc puny
rfc822 mml mml-sec epa epg gnus-util rmail rmail-loaddefs mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
mu4e-meta smtpmail sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils org-mime ox-org ox-md ox-latex ox-html table
ox-ascii ox-publish ox org-sidebar org-ql-view transient ov
org-super-agenda ht crm org-ql peg ts org-habit org-agenda
dash-functional ivy-posframe posframe mailcap move-text hydra lv
disp-table dashboard dashboard-widgets page-break-lines desktop frameset
rainbow-delimiters autorevert filenotify mark-multiple
smart-hungry-delete company-shell slime-company slime-fancy
slime-trace-dialog slime-fontifying-fu slime-package-fu slime-references
slime-compiler-notes-tree slime-scratch slime-presentations bridge
slime-macrostep macrostep slime-mdot-fu slime-enclosing-context
slime-fuzzy slime-fancy-trace slime-fancy-inspector slime-c-p-c
slime-editing-commands slime-autodoc slime-repl elp slime-parse slime
derived company-dabbrev-code company-dabbrev cap-words superword subword
gud apropos etags arc-mode archive-mode pp hyperspec browse-url
company-irony company-template irony-completion irony-snippet irony
irony-iotask company-c-headers flycheck-clang-analyzer flycheck-package
flycheck json company-prescient company skeleton package-lint rx
let-alist imenu finder lisp-mnt yasnippet-snippets yasnippet elec-pair
saveplace savehist tramp-cache tramp-sh tramp tramp-compat
tramp-loaddefs trampver ucs-normalize shell parse-time recentf
tree-widget dired-async dired-aux async find-dired wgrep counsel xdg
xref project dired dired-loaddefs swiper ivy-rich ivy-prescient map ivy
delsel colir ivy-overlay projectile grep compile ibuf-ext ibuffer
ibuffer-loaddefs thingatpt prescient org-bullets org-element avl-tree
generator org org-macro org-footnote org-pcomplete pcomplete org-list
org-faces org-entities noutline outline org-version ob-emacs-lisp ob
ob-tangle org-src ob-ref ob-lob ob-table ob-keys ob-exp ob-comint comint
ansi-color ring ob-core ob-eval org-compat org-macs org-loaddefs
format-spec find-func cal-menu calendar cal-loaddefs htmlize cl
use-package-bind-key bind-key easy-mmode paren beacon
use-package-delight linum-relative linum display-line-numbers hl-line
time minimal-theme edmacro kmacro cus-edit cus-start cus-load wid-edit
pcase spaceline-config spaceline-segments s spaceline subr-x powerline
powerline-separators color powerline-themes dash delight advice cl-extra
help-mode use-package-ensure use-package-core finder-inf slime-autoloads
info package easymenu epg-config url-handlers url-parse auth-source
cl-seq eieio eieio-core cl-macs eieio-loaddefs password-cache url-vars
seq byte-opt gv bytecomp byte-compile cconv cl-loaddefs cl-lib time-date
mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame 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 charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 821060 74591)
 (symbols 48 74728 1)
 (miscs 40 189 389)
 (strings 32 212292 20890)
 (string-bytes 1 6679386)
 (vectors 16 84144)
 (vector-slots 8 1525650 34128)
 (floats 8 595 548)
 (intervals 56 1501 448)
 (buffers 992 16))

--
<:3nn~~
   <:3nn~~
      <:3nn~~