The bug
If a piglin is on a minecart and when it converts into a zombified piglin, it sinks into blocks. It also happens with the baby piglins that convert into zombified piglins which makes them suffocate into the blocks.
This bug also works if the minecart is boosted by the powered rails, which results the converted zombified piglin to sink into blocks. (See the video below that says "The Result but with the powered rail method")
How to reproduce
Put rails and a minecart
Spawn a piglin
Put the piglin on the minecart (make sure the minecart doesn't move and be placed on full-block spot, or the bug will not work. Or have the minecart boosted by the powered rails)
Wait for it to convert into a zombified piglin
β β Notice it sinks into blocks
Linked issues
relates to
Attachments
Comments


Do you have a picture of the Zombified Piglins sinked into blocks while on boat part?Is the reproducing with the boat the same thing as the minecart one?
EDIT:Β It doesn't affect boats. Only minecarts.

It affects all mobs that convert while in a minecart, including z villagers.

I tried to do that with the other mobs that convert besides the Piglin but it doesn't work for me.

So, I just found out that the bug existed since 20w22a when the Zombified Piglins started to raise their arms like a Zombie. If you try to produce the bug in the snapshots before 20w22a, it will not work.
So, here's some proof of how long the bug has been there:

Cannot Confirm/Reproduce in 20w28a.
Probably fixed already.

It seems that there are different results in reproducing this issue:
If the minecart the piglin is riding is slowly moving, it stays on the minecart after turning into a zombified piglin.
If the minecart doesn't move at all, the piglin that is turning into a zombified piglin dismounts the minecart, cause it to sink into the ground
If the minecart is boosted by a powered rail, the piglin riding on it dismounts after turning into a zombified piglin and sinks into the ground too

Updated to also contain the powered rail method.

Seems like the Piglin Brute no longer sinks into the blocks when it zombifies, but it still affects the normal Piglins to sink into blocks.

When you push the minecart, the mob will be at the correct hight.

Well, yeah. But not only when it is pushed. It also happens when the mob goes directly at the minecart or falls into it, but it still has the same result.
However, it still affects the bug if you use the normal Piglin.
Can confirm.
Also affects boats.