NSimSun font, Chinese name is 新宋体, this is a Chinese font, its spacing is 90, it should not be included in the monospace family
In /etc/fonts/conf.d/40-nonlatin.conf, he actually has the following code
Also in /etc/fonts/conf.d/65-nonlatin.conf
When storing in a monospace family, the spacing value should be at least 100.
The same is true for SimSun (宋体) font
The package owning the files in question is fontconfig
$ pamac info fontconfig
Name : fontconfig
Version : 2:2.16.0-2
Description : Library for configuring and customizing font access
URL : https://www.freedesktop.org/wiki/Software/fontconfig/
Licenses : HPND AND Unicode-DFS-2016
Repository : extra
Installed Size : 1,2 MB
Groups : --
Depends On : bash expat freetype2 glibc libexpat.so=1-64 libfreetype.so=6-64
Optional Dependencies : --
Required By : appstream ardour cairo chromium electron32 electron34 ffmpeg ffmpeg4.4 firefox gd ghostscript gimp gtk2 gtk3 gtk4
gtksourceview5 imagemagick lib32-fontconfig libass libbluray libcupsfilters libreoffice-fresh libxft pango plasma-workspace
plymouth poppler qt5-base qt6-base qt6-webengine steam-native-runtime webkit2gtk webkit2gtk-4.1 webkitgtk-6.0 wine
Optional For : mlt
Provides : fontconfig-docs libfontconfig.so=1-64
Replaces : fontconfig-docs<2:2.13.93-1
Conflicts With : fontconfig-docs
Packager : Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Build Date : tor 23 jan 2025 02:37:33 CET
Install Date : fre 24 jan 2025 08:37:38 CET
Install Reason : Installed as a dependency for another package
Validated By : Signature
Backup files : /etc/fonts/fonts.conf
You should go upstream to report such issue.
What the man said. 