Alright, some of y'all in this thread must literally have no interactions with real people if you think Uzaki is toxic or a horrible person.
Shit talking exists, even among good friends. Sometimes it's because you're good friends that you can shit talk. Fuck I have some friends that shit talk me and I do it right back, I have others that don't and I don't do it to them. Heck it happens between my wife and I; I say something about her, she replies, "Unrelated but you got life insurance right?" She says something about me and I ask if she's looking to get disciplined she should just ask directly.
Uzaki though isn't just a friend, she's gonna end up the dude's wife. She's a Tsundere cause of all the people she interacts with in daily life, she ONLY shit talks her senpai, the one person that everyone else can see they got chemistry going on (remember pretty boy bro that asked if they fucked yet?)
Consider this; she brings stuff to cook him a homemade meal, gets mad being compared to her mother and changes her speech, even if just to annoy her senpai, STARES AT HIM WHILE HE'S ENJOYING HIMSELF WITH DAT SMILE ON HER FACE.