Same with my mom~
Before she would always called me a lesbian even tho I dated both men and women (and eNbIeS but she doesn't believe in them). And after i came out as trans, she calls me gay. (Both as insults btw)
My brother thinks the same but I don't judge him I accept that he doesn't understand how it works. I want him to learn for himself in a healthy way, not in a toxic way because I love him.