Camera is being used by another application -- which one?
MicroSnitch or OverSight might help. See https://tidbits.com/2020/07/22/feeling-paranoid-micro-snitch-tells-you-if-your-mac-is-spying-on-you/
EDIT: these are for macOS, not iPadOS.  My apologies.  I'm leaving it here in case these references are useful to others though.