Moved into new house, stand alone shower drain leaking

3 months after moving into a house and noticing kitchen ceiling dripping water every time wife takes a shower, ripped off the drywall, noticed it has been repaired multiple times, probably to cover up the leak, and see what looks like a flange that's too big or a pipe that's too small for it and packed with something? Would I need a whole new shower since from the top as well, almost looks like they melted something around it instead of repairing it properly in the past? Appreciate any help.

If that is a standard shower drain then you should be able to replace it with a Jones Stephan's drain. Especially since you can get to
it from the top and bottom. Look it up and there are some videos that you can see how its hooked up.

That looks like the shower base is cracked.

That drain fitting is probably sized for pvc/abs/cast iron. The OD of copper is smaller so they tried to seal it with epoxy or resin.