Pinta, the Cross-platform alternative to PaintNET has not been updated in 4 years.
I think the problem is that .NET Runtime is only available through Microsoft repositories.
Mono is now integrated into the broader .NET runtime architecture.
Mono runtime is used in specific scenarios (AOT, mobile, WASM).
So Pinta now needs .NET Runtime 8. I was able to build it on Tumbleweed with Microsoft repository added.
https://packages.microsoft.com/opensuse/16/prod/
I understand that packages in Tumbleweed cannot require packages outside of its repository.
It probably wont be possible to distribute DotNet with OpenSUSE OBS.
Therefore I think Pinta should be removed from Factory.
Another discussion here a year ago, but Pinta is still included. It is not possible to comment on the package in OBS. Its maintainers have probably just forgotten about it.
For KDE we have Krita which I think is just as good as Pinta. A Gnome alternative I think there is MyPaint (considering Pinta is a GTK application).
If anyone really want Pinta, they can install it through Flatpak and Snap.