So far I was able to run those non-working flatpaks and chrome-based browsers in a VM using X11 and GNOME. Also some people already pointed out that the issue might be with wayland and some flags, especially OZONE flags they set for electron apps: Wayland - ArchWiki
Then others claim that with similar settings on Arch steam works. The testing branch is ready and similar to Arch stable. You can try to switch to that. For now I still don’t get what might cause that issue. There were several electron updates also included within this update-set.