(FAANG researcher):

The first few tech rounds tend to be the same.

Then there is a set of research interviews and usually a research job talk.

The main observation is that hiring researchers, after passing basic tech rounds, is much more about taste and how people subjectively rate someone's research. It's insanely competitive, but in a sense it is also easier than pure SWE because there are not as many whiteboard hurdles to pass. You just can't really leetcode your way into the role, without a good track record with really interesting research most teams will not be interested.