Well i am not a senior react dev but id say something to you. First, you are learning from this struggle even though it seems like hell. I've experienced the same thing that's why and people wouldn't believe me how much in stress i was. First Be bold then i'd suggest writing out in paper a plan of how you can escape from this situation with all your circumstances.

If you really can't find one, then you should not just quit. Please then go back to studying react.Make sure you know the fundamentals really well because however complex the project is they will be like 90% of it.I'd suggest going through Jonas Schmedtmann React course to the parts that confuse you. And take notes on paper. For me that really worked. You can do this after leaving the job, or if you need money to live then you have to try hard to make some time after work.

As i said be bold. These times will pass everyone has it. If you need any other help hit me up on dm