I'm starting to think that your flatpak runtimes might be corrupted.
You can try reinstalling the one used by steam. Uninstall with
flatpak remove org.freedesktop.Platform/x86_64/22.08
And then install it again with
flatpak install org.freedesktop.Platform/x86_64/22.08
To eliminate any other potential issues I'd recommend deleting the steam user folder as well before launching it again. Like I told you earlier.
Edit: It's hilarious, I find many people having the exact same issue but never with the Flatpak version. Some even use the Flatpak version as a workaround. Very weird.
All this is seriously so weird...
Okay, so the runtimes were fine, good to know. Btw, you can remove runtimes without first removing the apps that depend on them. They just won't work any more until you install it again.
Not an official one, but this should do the trick if you really want to delete everything. If you want to, you could back up the user files for your other Flatpaks first.
1.
flatpak uninstall --all --delete-data
2.Remove flatpak with your package manager
3.
sudo rm -rf /var/lib/flatpak /var/cache/flatpak ~/.local/share/flatpak ~/.cache/flatpak ~/.local/share/flatpak ~/.cache/flatpak /etc/flatpak
4.Reboot
5.Install flatpak again
6.Add flathub
7.Install steam
If that also doesn't work, I'm 95% certain it has to be one of your system packages. Weird that a system package would break any Flatpaks though... What distro are you using anyway?