So, given that this is across multiple snaps, and the workaround doesn’t stick anyway, we need to figure a way to avoid this affecting users on an ongoing basis. Is there a bug already reported against $something to track that?
It sounds more like it is a bug in the desktop-helpers or in snapd’s font caching that happens during a refresh than it is with the interface itself.
What writes the file $SNAP_USER_DATA/.config/fontconfig/fonts.conf ? It seems like since it is in $SNAP_USER_DATA that it would be something the desktop-helpers would be writing.
this issue should be fixed years before
Maybe you know how to fix it but the solution provided by @oSoMoN fix the problem for short time and his solution want me to modify files that removed after any new update for the Snap package