I always try to give everyone I’ve interviewed the benefit of the doubt. You never know what’s going on in their lives, and even if they fail a trivial question it doesn’t mean they are faking the ability to code.
I joined Facebook back in 2018. Didn’t study at all for the interview and passed somehow. Then I probably conducted 200-300 interviews in my time there, so I became quite familiar with the questions. My performance ratings were all exceeds or greatly exceeds. I voluntarily left on my own after four years to join a unicorn startup. I didn’t prep for that interview either but passed it too. Well, the startup failed and many people went back to Meta. So I actually prepared quite a bit this time and scheduled a mock interview with them. The mock interviewer said I did great and not to change a thing. When it came time for the real screening interview... I failed the matching parentheses question.
I generally try not to make excuses. Almost every interview I’ve failed has clearly been my own fault. But in this particular one the interviewer kept interrupting me every two seconds and I absolutely could not think. I had done matching parentheses many times before in practice, but the constant interrupting rattled me to the point where I totally lost focus and bombed it. Not a great experience.
So yeah, I’d just recommend giving people the benefit of the doubt. Everyone has difficult moments occasionally, but it doesn’t mean they’re stupid or can’t code.