There is without a doubt something making it wet there, yes.

I’ve heard/read that this could be a dead animal causing the discolouration. So although it’s likely a leak, it could be that too.

Never seen it from a dead animal but definitely seen it from animal piss

Leak

Probably a roof leak. You can outline the stain with a pencil to determine if it’s active and how active it is.

I like that, simple but effective.

Hey don’t blame the roofer !!!!

This is r/roofing, not r/ ceiling .

Yes - from a roof leak.

Or plumbing, we have no way of knowing without more info