When im inside the big underwater base structure on abyssal chasm, the deep ones tend to easily suffocated even when theyre not completely covered in block. Current case that i have been encountered is that:

1. Deep One knight suffocated near rusty scaffolding
2. Deep one mage suffocated when below the structure even if the only thing that touched/clipped through the block is only the upper area of its head.

im not sure if this is due to the hitbox or if its due to the structure shape that makes them easily suffocating (The structure i refers to is the one with submarine inside of it and have glass roof