There is a theory about that. Of course you are right with what you wrote. It is about the side of the coin when the MC Maya warned.
But what if the MC does not warn Maya?
In the EP5 Hangout of Josy/Maya/MC, we see the list of Quinn's tasks that Maya and Josy have to do. Some tasks are already crossed out, so they are done. Among them are sexual tasks that are already done.
When the MC is with Maya, the sexual tasks that had to be done with a man are done with the MC (end of EP3). But making out with a woman, which is also done, Maya definitely didn't do with Josy. How also.
Josy and Maya have sex for the first time in B&R in EP6, which can be inferred from Maya's thoughts during sex. But that's in EP6 and the list is from the end of EP5.
If the MC doesn't warn Maya, Maya will probably have done that job with Quinn. Yes, Quinn. In EP3, there is a Rooster entry from Quinn where Quinn writes that she and Maya spend some time with mother and daughter. Also in EP3, we find a Quinn-branded lollipop on Maya's wall shelf. See spoiler. This lollipop was put there specifically by DPC because the lollipop is not there before and after. But that probably only happens when the MC doesn't warn Maya.
If the MC did warn Maya, I suspect there are three possible candidates. KRJ, Ashley, and Sarah. But there is only weak evidence for this and is therefore speculative. But Josy has seen the evidence videos and knows which girl did it. She is pretty shocked.