This is a known issue:
https://github.com/flameshot-org/flameshot/issues/3700
Some people have reported that following these steps and rebooting have fixed it for them:
https://flameshot.org/docs/guide/wayland-help/#can-t-screen-anything-on-wayland-gnome
Anachron :void: (npub1yn7…q0l5)