Player's that are swimming have an incorrect hitbox, though the camera height still changes correctly
Steps to Reproduce
*Make a 1 block gap
*Go into water and try to swim into it
Observed Results
*You can't go into the 1 block gap while swimming(you can't even swim at the very top of a block on the ceiling)
Expected Results
*You can go into a 1 block gap while swimming
(In short, you can't crawl and swim through 1 block gaps)
Related issues
is duplicated by
relates to
Comments

Could be related to MCPE-55862, MCPE-55864 and MCPE-54255. All of these bugs can make you have the incorrect hitbox while swimming and gliding.

Affects 1.16.21

Affects 1.16.40 Hotfix

I cannot reproduce this in 1.16.40, it is a beta-only bug as far as I am aware. How are you reproducing this in 1.16.40 @unknown? That version should be removed from the list.

bugsbugsbugs I'm sorry, i made a mistake typing 1.16.40 Hotfix. I'm sorry. This is cannot be reproduced in the version 1.16.40 Hotfix.
This issue affects anything that can change the player's collision. That includes tridents with riptide and elytra wings.