Hi @Norse_Harold,
Thank you for caring.
The rpm package that comes from Fedora runs without issues and doesn't show this error (It also has better performance).
SuperTux flatpak runs without issues, and this error doesn't appear.
Today, I installed WarZone2100 (net.wz2100.wz2100) from Flathub, and I experienced this exact same issue (no audio, and same error message).
This could be related to the Flatpak builds, or my Fedora configuration. If anyone can try to reproduce on other distros, that would be helpful.
Regarding your question: I check Flatpak permissions using an app called "Flatseal".
Looking for Jack on my system:
#dnf list -C *jack*
Last metadata expiration check: 3:15:23 ago on Thu 24 Nov 2022 12:51:06 PM EET.
Installed Packages
pipewire-jack-audio-connection-kit.x86_64 0.3.60-5.fc37 @updates
qemu-audio-jack.x86_64
Trying to uninstall either would remove so many things (including ffmpeg and some virtualization packages).
I never mess with audio in my distro (if it's not broken, don't fix it! ), so my experience with these things is almost /dev/null . I'll look into these details/links tomorrow, but no promises, as I don't want to break my main setup. I'll let you know if I have any updates. Meanwhile, any attempt to reproduce is much appreciated.
Thanks again, and have a great day!