Do you use App Armor?
It seems pretty easy to use on Ubuntu. For example, this can deny GIMP from accessing microphone, camera, and screen recording.
sudo nano /etc/apparmor.d/usr.bin.gimp
# Deny camera access
deny /dev/video* rw,
# Deny microphone access
deny /dev/snd/* rw,
# Deny access to shared memory and temp files for screen recording
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