The information on https://flathub.org/apps/ca.victorz.acr.AssaultCubeReloaded is outdated, specifically the version number and license.
I think appstream.patch needs to be updated, or it should be removed and replaced with the upstream .freedesktop folder, if that's where it should be maintained, which I think you said is the case in acreloaded/acr#265 (comment).
The information on https://flathub.org/apps/ca.victorz.acr.AssaultCubeReloaded is outdated, specifically the version number and license.
I think
appstream.patchneeds to be updated, or it should be removed and replaced with the upstream.freedesktopfolder, if that's where it should be maintained, which I think you said is the case in acreloaded/acr#265 (comment).