This was pointed out in another comment but I will basically echo it to just give that call a boost: Point your instructor to well-regarded sources for introversion and extroversion, and let them know that the labelling in their note is not only inaccurate, it falsely attaches a wrongly defined word onto problematic behaviours that have nothing to do with what introversion and extroversion is, which is not good because it propagates a false narrative.

If your instructor doesn’t seem cooperative and insists on being correct, talk to other instructors that you trust, or even go to those with more authority to tell them about the issue. If you can’t get anyone to actually do something, I suggest you change schools immediately, and call the school out for what they did.

Maybe it’s just one of those days, but I have no tolerance for this sort of false narrative being spread, even if the original intention is innocuous, and especially in a school. Being forced to act in a certain way that deviates from one’s personality to not be perceived as a problematic person, especially over a badly-informed opinion, can have lasting negative consequences to children and adolescents. I’m tired of seeing introverted friends and family members suffer over the fact that they’re introverts, to the point where they will deny being an introvert and even echo these sorts of statements in order to blend in.

The fact that Reddit can still tell you that the user deleted their account is proof that not all of that user’s data in their systems are deleted. It may just be a flag in an account that marks them as “deleted”, and so whenever data about that account is being retrieved, their API server will look at that flag, and tell the recipient that the account is “deleted”. People in the software industry calls this “soft deletion”.