The floor actually look OK. Maybe you can check with your contractor if they can do a chemical wash on the floor tiles and patch up the grout lines.
Mine is worst, the previous owner had use anti-slip mat, so there are black stain where the mats were. My contractor tried acid also cannot get ride of it. It is the common toilet, so I let it be. My master bedroom toilet, I hack wall & floor b'cos they had a bathtub in it (roll eyes).