Imo the hp bloat coupled with the gamey abilities make just about every fight in thr underdark play out as if you are fighting a bunch of superheroes.

For example: Hook horrors can do over 20meter jumps that do aoe damage, shockwaves, have multi attack. And you fight 4 of them. You can beat it. Thats not the point. The point is you arent fighting hook horrors.

I saw multi attacking minotaurs move 200 feet in 1 turn, a beholder fly an entire screen away and using rays he shouldnt have.

If you want to use the dnd license then use it, but dont dress monsters up as classic dnd monsters and give them all new abilities....