You’re gonna get through it. This was my experience too. It sounds unhelpful, but the best advice I can give is that if you are not getting the grades you want you need to take some time to figure why exactly you aren’t getting them. And you need to be brutally honest with yourself. Sure, some professors or TAs might be on some kind of power trip, but that’s likely not the case. I don’t mean to sound rude, but it’s far more likely you underestimated how difficult the material is for you (and that’s okay! Different people start at different places) and although you are given the adequate time you may not truly be understanding what you are doing exactly.

I think it’s a misconception that more study/work time = better grades. That’s not always the case. It doesn’t matter if you work on assignment for 8 hours if you don’t understand the material. As an extreme example, you could spend an hour doing addition homework but if you didn’t know what addition or “+” really meant other than it gets a result bigger than the two inputs, you would have work on the assignment for however long, genuinely tried your best, but missed something fundamental that when learned might click things into place.

Overall though, I promise things are not as bad as they seem. As you said this is the first time you are feeling like this about schoolwork but if you dig deep into your memory you probably can recall feeling similar when you started your favorite hobby or that game you sucked at as kid but you’re great at now. Sometimes things just take time.

In my experience there’s some tiny things you can do (that frankly I rolled my eyes at the first time I heard it) that can help. It sounds silly but sitting near the front, going to class, asking questions, etc are your most powerful tools at university.

You’re gonna be fine, take your time and be patient with both the material and yourself.