It's my mistake, I actually set to the peaceful mode. The game is running correctly.

Pufferfish nolonger attack mobs in experiments.

How to Reproduce:

1. create a new world with Update 1.20.
2. summon some pufferfish in the water.
3. change player's game mode to survival and close to them.

You can see that pufferfish don't attack player anymore.