Let the landlord know that you have a mold issue in the bathroom. They’ll clean the mold and most likely replace the floor with a low-cost vinyl. Having resolved the issue within a reasonable amount of time, they will thank you for letting them know there was an issue. Everyone has a nice day.

Here’s what I’ve seen happen if the landlord strays from the above. The tenant will claim to suddenly come down with some type of mold related health issue. [fast forward past the details] They will go to the court house where there are lawyers waiting outside claiming to work for free on the tenants behalf. Lawyers will claim that there was some type of habitability issue. The lawyer bills the landlord. The landlord still needs to clean up the mold issue.