Negative Thoughts on Work

Hello, I made a decision for financial and other reasons to stay in my job until February 2024. That’s only 15 months away and I like my reasons.
However, I still have a lot of daily anxiety. One reason why I want to leave is that there is a core element of the job that does not come easily to me. My managers are asking for things daily that are hard for me to deliver on. I am trying my best and learning but am putting out B- (or C?) work often.

I get criticized for my work. If you want to make it a C instead of a T, I hear “words” like “it needs to be better” “this is not good”…

I guess I’m not sure what to think about this. As someone who wants to do well, should I just not care since I’m leaving? Should I hustle more to try to get it to a B instead of a B-? None of these feel good.

Can you help me find a better thought or should I change my circumstance?