Seems like a really stupid ban. Unless you’re overly online and/or up on the latest trans discourse in the US, calling women females is at worst a little weird, but ultimately innocuous. Could easily be an ESL issue also.
Now if there is good reason to believe OP is intentionally using it in the weird incelly way, sure that’s bad. Although unless OP is like intentionally missgendering or otherwise harassing people with the word, I personally think it’s way overkill to police it even if he does mean it in the incel type of way…
Edit: Oh wait, I’m slow. The punchline is probably that the “female” in question is either a man or trans. Yeah in that context the probability that OP is intentionally being weird is probably much higher…