The Bug:
On Bedrock edition, dolphins will follow players riding Nautiluses just like they do when players ride boats.
This does not seem to be the case in Java edition. In fact, it seems like Java dolphins no longer even follow boats either, despite doing so before. Definitely not player-ridden Nautili
What I Expected:
Dolphins to follow players riding Nautiluses just like Bedrock, as mojang aims for parity.
Can confirm, I reported dolphins no longer following players in boats separately and linked it as related.