> I have flatpaks from several years ago that no longer work (Krita) due to some GL issues.
That’s an example of Linux GPU APIs being unstable in practice, and container images not helping to fix that.
But I suspect "GL issues" (i.e., GL API stability) is being mixed together with e.g. mesa issues if mesa is being bundled inside the app/in a "flatpak SDK" instead of being treated as a system library akin to what you would do with DirectX.
Mesa contains your graphics driver and window system integrations, so when the system changes so must mesa change - but the ABI exposed to clients does not change, other than new features being added.
I'm running Loki game binaries just fine today btw.