Bath fan
A dripping fan can be steam. It can also be a pipe above the fan.
Winter steam hitting a cold duct looks like a leak. A supply line in the same joist bay is a leak. The grille is a bad place to guess.
Does it only happen during or after a hot shower?
Steam is more likely. A drip at 4 a.m. is not steam.
Look at the suite above the fan.
A wet fan grille under a bathroom is a plumbing suspect.
Do not keep running the shower with the fan off as a test.
You will only make more steam.
Questions people ask
Should I replace the fan first?
Not until you know whether water is coming from the duct, the roof, or a pipe.
Can a fan leak into the light beside it?
Yes. Treat wet electrical as safety first.