@BlindfoldPlayer your rating in any pool does not mean anything except relative to the players in that pool. When the composition of the pool changes - your rating changes. This is normal and appropriate. There's been a lot of interesting events on Lichess that have emphasized crazyhouse so I'd assume the pool composition has also changed substantially in that time as well.
This is also why computer ratings are pretty silly. Saying Stockfish is rated 3400 or whatever is meaningless. That's in an incredibly closed pool. You cannot rate a computer, relative to human ELOs, without playing in the same pool as those humans!
It's also the same reason you can't really compare Fischer's 2785 to Carlsen's 2882. That the ratings remain optically comparable is an unfortunate coincidence.