I find it a little disturbing that the top rated answer that people reached for is to bring in Title IX claiming this is discrimination.
That said, the professor is a mandatory reporter under federal law. Either she is aware of violations and has reported them, or she doesn’t believe that what is happening crosses that line.
Especially when she writes that students have complained to her. If it even begins to sound like a Title IX violation, you interrupt to tell them that you are legally required to make a report of anything they tell you and offer to let them continue talking or that you will personally escort them to the university office where they can talk to someone that is not legally required to make a report. You absolutely do not solicit the internet for advice.
So this is dumb, creepy, and uncool. But it’s not a Title IX issue.