A lot of FAANG engineers report that the interview was the hardest thing that they've done, harder than anything they do as part of their actual job

"Interviews are hard in that they have absolutely nothing to do with your day-to-day job. If I were to go through the interviews again right now I'd make a massive fool of myself.

I'd say it's basically common knowledge that prior to making any hops, you've got to take at least a month or two to grind leetcode problems so that you're back in that head space where you can solve pointless problems with high efficiency.

Interviews are also hard because, if you end up with the personality type which views interviews as a chance to show how much more clever they are than everyone, then you've already failed. Their ego is tied to their "high bar" and impossible question set, and you're just fodder for them to show off that "high personal bar" during the de-brief."