Falling from a height in a boat deals fall damage when the intended mechanic is to not deal damage, see MCPE-149490 / MC-105103.
Steps to Reproduce:
Build a platform high in the air
Place a boat on the platform
Get in the boat
Switch to Survival mode
Ride the boat off the platform
Observed Results:
The player takes fall damage.
Expected Results:
Boats should negate fall damage.
Actually this is an old bug since 1.17 i reckon