I have seen my fair share of ‘bits’ in the studio.
I can tell you that I was once wearing a new yoga suit that, shall we say, compromised me. The teacher noticed and didn’t say anything until after class. I couldn’t believe it.
Now you could say that it shouldn’t matter and what on earth were you doing looking in that direction!!!! But even though that is a valid point of view, there are more things to consider.
I am a great believer of coming out with stuff like this. And directly to the person in a discreet way. I would approach them personally, make sure that no one else is around (or ask for a few moments by themselves) and say, I am not sure if you know this but in many of your yoga poses your shorts are not covering you sufficiently. I would probably also add that you are not the only person to notice.
You may find this person is not concerned in the slightest. That happens. But it can be offensive to others. So if their exposure bothers you and not them then it is important to a) let them know that others notice and b) let them know that you are requesting that they wear shorts that insure coverage.
If your personal approach doesn’t work then talking with the teachers or studio owner is the next step so that a studio policy can be instituted.
It is my opinion that if you have to adjust clothing to make sure you are not flashing your bits, or if you are wearing clothing that does expose you unnecessarily then it really doesn’t have a place in your practice in a public studio. Distractions should always be minimized.