I built a portal way out in the nether so I could access some new terrain to look for a camel, but the portal caused a chicken to suffocate when I travelled through it.
The portal in the nether was at -1500, 15, 1 and the seed is -5208210088792058538
The portal generated at -9998 68 11 in the overworld and apparently a chicken was there and it spawned on top of it.
Marking this as Plausible as I have reason to believe that this potential problem exists. I'm not sure if this would be a valid issue though, since similar things like trees don't check if entities are inside of them before growing; the trees will just grow and entities can occasionally suffocate inside of them as a result.