I have recently switched back to GNOME as the newest release fixed a critical bug that was preventing me from using it. In the time off from using it I went to KDE, then a few WMs/Compositors (i3, DWM, Hyprland) and then went back to GNOME. On returning, all the apps looked like kde themed. This was expected, so I used Tweaks to change the icon theme etc. back to Adwaita. But this still left the GTK apps with weird spacing for whatever reason.
I’m pretty new to the GNOME Discourse page, sorry if I’m using this wrong! (P.S: Why does it take 9 million years to upload a screenshot?)
Did you uninstalled KDE and installed GNOME on the same system? Go to Tweaks and reset every theme and see if it will help. If it won’t, consider clean reinstall. These two don’t like being installed on the same machine