Locked red door in the conservatory mission after deafening the two brute chieftains

Haven’t been able to see anything about this one but there’s a locked red door on the conservatory mission. Instead of going to the objective you go up about 60 seconds of grappling you’ll come upon it. Anyone know anything about it? I’m a new user so I guess I can’t upload an image. Someone add it if you can find the door!

The elevator takes you up but it just ends the level before you get there.