(I don't know if the bug has already been reported, I didn't find it, I'm really sorry if it is already the case)

Description

Sail around a dolphin with a boat will normaly tease it, so it should start to do circles and jumps around your boat and get a bit faster. But since 1.15-preX, the dolphin speed boost seems to make it abnormally very fast. You can barely see it cross the sea in a split-second.

How to reproduce

1. Go to an Ocean biome, then find a dolphin or summon one with the following command :

/summon minecraft:dolphin ~ ~ ~

2. Get a boat and mount it :

/give @p minecraft:oak_boat 1

3. Try to sail around the dolphin, until it spots you. Then sail in straight line. You'll see that the dolphin will get abnormally fast.