Why is my mom like this?

So last night I went to the gym with my mom to do a hip hop class (1 hour long) after the class I was ready to leave since we always just do the class and go home. She gave me an attitude and said no we’re not leaving yet! I told her I was tired since I went to the gym earlier that day too and it’s late already. She was like “don’t be a fuckin asshole, give me 35 min”. She always resorts to calling me names. Last week she said I was acting like a “bitch” just because I didn’t feel like going hiking with her and my sister. She always says rude stuff to me, I’m 24 years old she needs to respect me. I never call her names so she should give me the same respect, right? I’ve explained this to her many times but she doesn’t change. Yet, she never speaks to my oldest sister like this, cause she knows my sister would literally not speak to her for good.