Hi Sara
I can honestly say that in years of having my own private and public studios I have never had a problem with mold.
I know that many others who come to this forum have bathroom studios and other useful spaces. I hope that they can tell you their thoughts.
The main thing is to have plenty of ventilation. And of course clean it. Your general bathroom routine should do it. Of course if you have the offer of a purpose built yoga studio well then that is the best option.
Namaste
Gabrielle 🙂