Still getting the error trying to launch Roblox from Firefox on any of my comps after the 08/31 update.
Sep 07 11:38:10 username plasmashell[2056]: [Parent 2056, Main Thread] WARNING: Could not launch default application for URI: Desktop file didn’t specify Exec field: 'glib warning', file /build/firefox/src/firefox-117.0/toolkit/xre/nsSigHandlers.cpp:167
Sep 07 11:38:10 username firefox[2056]: Could not launch default application for URI: Desktop file didn’t specify Exec field
Firefox Flatpak doesn’t appear in Pamac? I wanted to test. Actually, as I’m writing this, Pamac doesn’t appear to be showing any Flatpaks anymore…
EDIT: after pamac updates I could install ‘Vinegar’ Flatpak so my kids’ brains could successfully turn to jelly for hours on Roblox. 
I’ll try to run a couple of games for longer to see if I’m still getting amdgpu Kernel errors coinciding with freezes, tonight.