This is the back bathroom in the old house I am remodeling and you can see from the colors I probably should have just said "this is a retro bath" and left it alone! I'm sorry, I could not take the blue and pink, and, of course, the floor had to go!
Well the area where you see the square in the floor had been replaced once before and we discovered the reason it kept rotting out was a leak between the sink drain and commode! No way to get into the backside, so tile had to be removed under the sink to get to the leak>
So leak repaired and floor tiled!