See screenshot from GNOME Screenshot uploaded here: https://i.postimg.cc/tgWx2DjT/Screenshot-from-2022-05-19-09-18-57.png
Only the upper left quadrant of the screen is captured, the rest is left black. I'm not sure when this regressed, but it didn't happen before.
Using Solus Budgie, packages fully updated.
My screen resolution is 3840 x 2160 (16:9) with 200% UI scaling.
$ gnome-screenshot --version gnome-screenshot 41.0
My guess it could be something with mutter, but I'm not exactly an expert on this. And I can't even begin to try and reproduce this either which makes tracking down the issue a little problematic since I don't have a 4k display.
So thanks to @Harvey for testing this out on his 4k monitor, he was able to reproduce it in both 4k resolution and 1080p, but in gnome it does it just fine. And right now I'm just grasping at straws, but it might be something along mutter, specifically budgie-wm since it links with libmutter.
I am unable to reproduce this any more, so I am going to close this task as resolved. If the issue persists for the OP please re-open.