One interesting thing I saw from their project's development site:
We do not maintain the Flatpak package. Do not report issues related to Flatpak unless the issue can be reproduced with a native package, use Flatpak support instead Flatpakâthe future of application distribution
To answer your questions from the other thread:
Not that I know of, though I suspect most likely not since that would require a re-write on the source code.
The instructions from my earlier post would install the correct version for your operating system. Those — Bookworm, Trixie and Sid — are codenames for Debian branches; do not use those.
I would suggest trying the native package format from that PPA, or use Xorg, or both. It may just be the case that the Flatpak package is unmaintained or has something wrong with it?