Can you post a screenshot of Gimp and the cursor ? Is it the actual tool cursor - each tool has its own cursor icon Edit -> Preferences -> Image Windows has a Mouse Pointers section.
or Is it something like a brush outline, large brush = large outline? or The cursor you get outside the canvas, a pointer. (I think you already covered that, just checking)
Are you using a graphics tablet ?
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Well pop_os is closely tied to System 76. Did you buy one of their computers or install yourself ? If from System 76 maybe they can give some advice otherwise pop_os seems lacking in user support. There is a sub-reddit https://www.reddit.com/r/pop_os/ might get some advice there.
However, pop_os is based on ubuntu (and gnome DE) I use kubuntu 20.04 and have never come across a large cursor issue. Does your computer have a 4K display ? It should not make a difference but might.
The only setting I can think of at the moment is Gimp theme. Try Edit -> Preferences -> Interface -> Theme and select 'System' might / might not make a difference to the cursor. Otherwise, a trawl through the gnome system settings might turn up something, I can change cursor size here in KDE easily.
If nobody comes up with a solution / nothing works, do post the problem for the developers https://gitlab.gnome.org/GNOME/gimp/-/issues it might be something that can be fixed.
Edit: A quick search: 4K problems go back a couple of years, no fix https://gitlab.gnome.org/GNOME/gimp/-/issues/3742
but there might be one here: https://askubuntu.com/questions/972113/h...4k-display
or https://www.reddit.com/r/pop_os/comments...s_scaling/
or Is it something like a brush outline, large brush = large outline? or The cursor you get outside the canvas, a pointer. (I think you already covered that, just checking)
Are you using a graphics tablet ?
----------
Well pop_os is closely tied to System 76. Did you buy one of their computers or install yourself ? If from System 76 maybe they can give some advice otherwise pop_os seems lacking in user support. There is a sub-reddit https://www.reddit.com/r/pop_os/ might get some advice there.
However, pop_os is based on ubuntu (and gnome DE) I use kubuntu 20.04 and have never come across a large cursor issue. Does your computer have a 4K display ? It should not make a difference but might.
The only setting I can think of at the moment is Gimp theme. Try Edit -> Preferences -> Interface -> Theme and select 'System' might / might not make a difference to the cursor. Otherwise, a trawl through the gnome system settings might turn up something, I can change cursor size here in KDE easily.
If nobody comes up with a solution / nothing works, do post the problem for the developers https://gitlab.gnome.org/GNOME/gimp/-/issues it might be something that can be fixed.
Edit: A quick search: 4K problems go back a couple of years, no fix https://gitlab.gnome.org/GNOME/gimp/-/issues/3742
but there might be one here: https://askubuntu.com/questions/972113/h...4k-display
or https://www.reddit.com/r/pop_os/comments...s_scaling/