Why do some classmates treat me like I’m dumb even when I’m not?

Why some of my classmates treat me like I am dumb but they clearly understand that I’m not. Like, I knew unreal engine better and we worked in one project together. One girl knew better than us. But when I offer something she was irritating. And when I try to do something she was so sarcastic when I couldn’t. While she is super nice with others.
And other girl, we kinda hate each other. But when I say something she is sometimes so so rude I act like I don’t understand something. For example for group project I was one who is acting, and I knew it. But I asked “will third group have actor?” And she acted like I said something stupid and said “you are the one who will act🙄”. Like I did practice for several times, of course I knew that I am acting in our group and asked about other group.
This kind of things irritates me so much.

Also when I was talking with teacher, and saying which program I use for editing, she downloaded same program and started using. She is copying me, but still treat me that way
Why do some classmates treat me like I’m dumb even when I’m not?
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