Maybe I missed it, but what do you think is/are the reason(s) they go so bad? Time pressure? Having an interviewer watching and judging? Etc. For me personally

Maybe I missed it, but what do you think is/are the reason(s) they go so bad? Time pressure? Having an interviewer watching and judging? Etc. For me personally, my brain goes completely blank at the problem statement, pretty much in the dark without a flashlight, and I have to work everything out by hand and hope that my code actually ends up being correct and reasonable. It's scary but I've ended up doing well.