I'm seeing several threads on Reddit about mouse issues. I found https://ludeon.com/forums/index.php?topic=54419.msg490455 on the forums but its very old for a bug like this. Is there any update on this?
Here are a list of threads on Reddit about this issue:
https://www.reddit.com/r/RimWorld/comments/oopk5q/click_and_drag_issues_on_linux/
https://www.reddit.com/r/RimWorld/comments/qnj7r4/any_update_on_the_linux_mouse_issue/
https://www.reddit.com/r/RimWorld/comments/ovcarv/mouse_pointer_not_accurate_moving_mouse_slowly/
https://www.reddit.com/r/RimWorld/comments/q7j8i3/ui_lag_with_slowmoving_mouse_cursor/
https://www.reddit.com/r/RimWorld/comments/ovp072/keyboard_and_mouse_inputs_not_working_correctly/
There might be more but this is what I can find. Affects all versions since 1.3. Affects vanilla and mods.
A bug report has been filed, with assistance from a linux user replicating it on Windows as well. I do not have a status update on the bug, but it is being looked into. Before that point I had collated all of these reports for the devs, though so it is being researched.