You can go through the roof by getting out of a boat Under the "roof"

Steps to Reproduce:
In a block, place a boat, now place a block on top of the boat
Sit on the boat

Observed Results:
You will appear on top of the block, same on java

Expected Results:
You will appear in the block what is below of the boat, not on the top block

Notes:
I am bad explaining, you can see the video for more info, the error also works on 1.16.4(java) 20w51a(java).