When I interview people, I give pretty straightforward questions. My goal is not to run some algorithm guessing game. If I'm interviewing for a senior FE position, I make sure they know enough about async patterns in JavaScript that I feel confident that they could build an event handler without dropping promises on the floor.
A back end position? Can they use (not implement, just use) a hashmap efficiently and do they think about boundary conditions in input sets (you'd be surprised how many people ignore punctuation when breaking sentences into words - they just do a split(' ') and call it a day.
This is really basic stuff. I'm always able to (a) filter out people who just need more time learning to code (or are too nervous to perform well, which is still a problem with even these whiteboard activities) and (b) prompt a discussion about engineering practices.
My criterion is simple: do I think I could see this person submitting code to my project without me needing to constantly fix what they write? It isn't about memorizing algos or anything.
Aaalso: I didn't study leetcode, and managed to get my job just fine. I know there's a reputation of the process being just algos, and I'm sure a lot of the interviews are. But not all of them, even at the FAANG.