Tha Ghast hitbox does not rotate with the body players can see. I believe this is the case for every mob, but this is especially problematic with both ghast mobs due to their size.
This creates significant issues when interacting with the ghasts, like shooting them or trying to land on them because the visual body is not accurate to where the mob actually is, especially at high rotation angles; it’s a real problem for example with minigames where you have to jump on the happy ghast, in many cases it looks like you should land but in reality you do not.
It might be time to revisit this as a follow up to MC-91376 , it’s been 10 years.
That’s the way Minecraft is.
This is not a bug per se, but a request for an improvement.