'21 M340xi central vent suddenly making noise when AC is on?

Hi all,

My '21 M340xi's center defrost vent that faces the windshield started making a noticeably loud low pitched noise when I drove the car this morning.

I tested it with the engine off, and it doesn't make the same noise if the AC is running without the engine on. If you turn the AC off while the engine is on, then turn it back on, it takes around 10 seconds before that vent starts making noise. It basically sounds like it's set to like a level 5 or 6 bars even when its at 1. From looking online, I'm not seeing a lot of answers about this other than that it could be a stuck actuator inside the HVAC system.

Has anyone else experienced this and figured out the cause? I also posted in Bimmerforums but haven't had anyone chime in yet.