The hitbox of Hoglins is the same as a pig's. This means they can fit through 1 block gaps and other small spaces they are not supposed to, and don't suffocate.
How to reproduce:
1. Make a area that is only 1 block tall.
2. Try to spawn a hoglin in it.
3. You will see the Hoglin can fit in to it.
Thank you for your report!
We're actually already tracking this issue in MCPE-65424, so I've resolved and linked this ticket as a duplicate.
That ticket has already been resolved, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
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