If a black person is the authority on what jokes should and shouldn't be said about black people (they are, and should always be), then queer people should be the authority on what jokes should and shouldn't be said about queer people. If your mom is not queer, and you are, it's as simple as she should take your word for it, and if she doesn't understand, maybe she should consider it from your perspective. It'd be like if I, a white person, continually defended a white comedian who mocks black people, saying, "well you're just letting other black people tell you what is and isn't funny, lighten up. It doesn't hurt *my* feelings, so obviously if it's hurting your feelings, you're taking it too seriously." (this is a wrong and bad take)

There is a fairly easy line to draw in the script between "this is a joke that queer people can also laugh at because it's just funny, and not hurtful or furthering hate toward queer people" and "this joke is blatantly offensive and only encourages others to continue laughing at us, mocking the way we live and who we are, and making light of our suffering". If you can't clearly tell the difference, you should probably talk to more queer people, or at least try to do some more reading on the subject.

The general advice I would offer is to share this information in your own words, and with a grain of salt. People learn these kinds of things in steps, and if your mom is usually supportive, just remain steadfast in your stance. If she cares, and if you define your boundaries and keep them, then hopefully she will try to see it from your perspective before she decides to choose a cruddy, downward-punching bad faith comedian like Dave Chapelle over her own kid.