I have two fifties in series for my hot water.
I think I will try to change this small section of pipe, just to be safe.
I will try to get to the tee in the wall without disturbing the adjacent bath. I will heat up the existing tee and pull it off the 3/4 supply. I can then either try to solder another tee (not very likely, but I'll try), or I bought a shark-bite tee that may work, but it's kind of bulky and this is a really tight space.
Any other options for a confined space?