Steps to reproduce:
1. emacs -q
2. M-x shell
3. echo start
sudo pacman -S nyancat
echo end
4. See, that "end" doesn't get printed.

~ > echo start
sudo pacman -S nyancat
echo end
echo start
start
~ > sudo pacman -S nyancat
warning: nyancat-1.5.2-2 is up to date -- reinstalling
resolving dependencies...
looking for conflicting packages...

Package (1) Old Version New Version Net Change
community/nyancat 1.5.2-2 1.5.2-2 0.00 MiB
Total Installed Size: 0.06 MiB
Net Upgrade Size: 0.00 MiB

:: Proceed with installation? [Y/n] y
y
(1/1) checking keys in keyring [####################################################################] 100%
(1/1) checking package integrity [####################################################################] 100%
(1/1) loading package files [####################################################################] 100%
(1/1) checking for file conflicts [####################################################################] 100%
(1/1) checking available disk space [####################################################################] 100%
:: Processing package changes...
(1/1) reinstalling nyancat [####################################################################] 100%
:: Running post-transaction hooks...
(1/2) Reloading system manager configuration...
(2/2) Arming ConditionNeedsUpdate...
~ >

In GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.36, cairo version 1.17.6)
of 2023-01-03 built on 2
Windowing system distributor 'The X.Org Foundation', version 11.0.12101008
System Description: Arch Linux

Configured using:
'configure --sysconfdir=/etc --prefix=/usr --libexecdir=/usr/lib
--localstatedir=/var --with-cairo --with-harfbuzz --with-libsystemd
--with-modules --with-x-toolkit=gtk3 'CFLAGS=-march=x86-64
-mtune=generic -O2 -pipe -fno-plt -fexceptions -Wp,-D_FORTIFY_SOURCE=2
-Wformat -Werror=format-security -fstack-clash-protection
-fcf-protection -g
-ffile-prefix-map=/build/emacs/src=/usr/src/debug/emacs -flto=auto'
'LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -flto=auto''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY INOTIFY
PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE
XIM XPM GTK3 ZLIB

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

Major mode: Shell
Minor modes in effect:
shell-dirtrack-mode: t
tooltip-mode: t
global-eldoc-mode: t
show-paren-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
tool-bar-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
indent-tabs-mode: t
transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg rfc6068 epg-config gnus-util rmail
rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map text-property-search seq byte-opt
gv bytecomp byte-compile cconv mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils shell pcomplete comint
ansi-color ring time-date subr-x cl-loaddefs cl-lib iso-transl tooltip
eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type
elisp-mode 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 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 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 simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 64126 11476)
(symbols 48 7189 1)
(strings 32 20848 1844)
(string-bytes 1 694151)
(vectors 16 14694)
(vector-slots 8 196111 12327)
(floats 8 24 36)
(intervals 56 801 1)
(buffers 992 12))