While poking around with F3+B to check if
MC-4077 has been fixed yet, I've noticed that player hitbox is also rendered in invetory dialogue for no good reason (and obscures a button in creative inventory).
Decided to create a new report because by the day
MC-4077 will get fixed "Decorative blocks" button in creative inventory should become unobscured by hitbox, but the hitbox rendering in inventory will still remain quite pointless. Sorry for possible inconvenience.