Weird, do you feel like sharing generally where this is? I’ve corrected grammar in my English writing classes plenty of times as part of peer review, even (gently) corrected another student on how they were using a racially insensitive term, despite the fact I’m white and they weren’t without it being an issue (they were an international student and we had been reading some stuff from the 1800s that used outdated terms).
For other classes I’ve had a mix of whether or not the professors care about grammar, but those that do have always been upfront about how to get in contact with free tutors on campus to check your work.
RMP is a crapshoot anyway on how useful it is; one terrible prof at my school is constantly leaving really obvious 5 star reviews for himself to override the hordes of people going DO NOT SIGN UP FOR THIS CLASS!!, while a fantastic professor I have has close to the same middling rating because she does a class that qualifies for fulfilling a gen ed requirement, and people who are uninterested in it just don’t like the class.