For this, the only solution is to hack the tiles in the bathroom to about 2 or 3 ft from the floor and do water proofing. If not, you may apply muro wall finishes which requires no hacking but I am not sure about the cost.

This is normally true that ground floor bathroom did not require waterproofing but unfortunately, any rooms or areas next to the bathroom will have issues shown in the photos shared by cwk3344. If you are retiling your ground bathroom, it is better to do waterproofing at the wall of the bathroom to about 2 - 3 ft high.