This. levels.fyi is quite accurate both in first-hand data and when discussing salaries with folks that are coming from companies represented on the site.
I speculate that one of the things that makes it hard to square with market data is that levels.fyi leads with total compensation which will include stock based comp. afaict people report their stock comp differently, sometimes it's the original offer value and sometimes it's the value at that time (which might be years after the grant was given). Since things are really going up right now... it can lead to some big numbers. These numbers are still real, but not necessarily what you would see in an offer.
The salary numbers, however, are spot on in my experience.
I speculate that one of the things that makes it hard to square with market data is that levels.fyi leads with total compensation which will include stock based comp. afaict people report their stock comp differently, sometimes it's the original offer value and sometimes it's the value at that time (which might be years after the grant was given). Since things are really going up right now... it can lead to some big numbers. These numbers are still real, but not necessarily what you would see in an offer.
The salary numbers, however, are spot on in my experience.