Another perspective: I keep an eye more on my percentage than on my elo. My lichess blitz rating is higher, but my % there is 67 (better than 2/3 of players) but my chess.com % is over 93% (!) which seems to indicate that the level of active players on Lichess is much higher, at least at my level (1700 blitz).
Actually, as chess.com has by far the most users, it just means that most of them are beginners, so your percentage is greater here.
It makes sense really, the average rating is constantly dropping here, because more and more people are opening new accounts.
That doesn't make any sense since the beginners improve as they play more. Your observation would only make sense if the rate at which new players joined were higher than the rate at which the previous batch of old players improved, which hasn't been the case since the Queen's Gambit boom. In fact, on Lichess, the average ratings increased since 2021 even once "inflation" has been accounted for (I put "inflation" in quotation marks because there was never any inflation; instead, there has been significant deflation - by around 100 points since 2021).
The actual reason that Lichess has a much stronger pool of players is that it has a worse domain name and basically no marketing, as compared to chess.com, which is very strong in both of these departments; therefore, the only people that know about Lichess tend to be seasoned players and/or those deep within the chess community, while practically everyone knows about chess.com. As a result, while the chess.com playerbase represents all active chess players, Lichess's playerbase mostly represents just the experienced/competitive players. The best way to verify this is by comparing the Lichess blitz percentiles to USCF classical percentiles: they are almost identical (once the ratings have been converted so as to be comparable).
Another perspective: I keep an eye more on my percentage than on my elo. My lichess blitz rating is higher, but my % there is 67 (better than 2/3 of players) but my chess.com % is over 93% (!) which seems to indicate that the level of active players on Lichess is much higher, at least at my level (1700 blitz).
Actually, as chess.com has by far the most users, it just means that most of them are beginners, so your percentage is greater here.
It makes sense really, the average rating is constantly dropping here, because more and more people are opening new accounts.