I got fog in the front camera of my XS the same way. To the point that FaceID stopped working. I waited a while for it to dry up but it didn’t - but I’d suggest waiting a little bit. In the end, I had to go to Apple and send the phone in & they more-or-less replaced the whole thing. Was not that bad though, only took them a week or so to get it back to me. Hopefully you won’t have to go through that, but either way make sure you back stuff up!

P.S. - just say “my phone lens got foggy” when you talk to them - don’t mention even bringing it near the shower. “Oh, I just noticed it one day” or something. They can be very picky about replacing phones that have water damage, although it should be covered. So just don’t make it extra obvious! Good luck.