Does your bug have a Mojira id? If so, what is it?
It's MC-262114 (https://bugs.mojang.com/browse/MC-262114)

What's the bug about? Why do you want it fixed?
Big mobs (ravagers, horses) produce a lot more lag when going through nether portals with nonstandard-hitbox blocks on the other side. It produces a lot more lag in complex portal-based farms.

Describe the solution you'd like
This bug was a "fix" to MC-80032 (https://bugs.mojang.com/browse/MC-80032), the easiest fix would probably just to revert it back to the way it was before.

Describe alternatives you've considered
I don't know any easy alternatives; the best-case scenario would be the best of both worlds, where mobs are both kept from suffocating when going through a portal and don't produce a lot of lag but I don't have logic to implement this.

What should the rule be called?
portalMobHitboxFix? idk