I just posted a similar thread and saw yours. I see it’s almost a year old but what did you find out? Is your engine an FSI? If so I don’t think it’s under the manifold, I’ve had mine off and didn’t see anything like that under there while changing injectors. I think it close to the throttle body and looks nothing like a conventional PCV valve. There’s a hose coming off a valve cover that attaches to the unit near the throttle body (I believe). My engine is running rough and when I remove the oil cap I get the same suction and the car starts to run really rough. OEM I think the part is over $300 so of course we want to properly diagnose the problem.

Don’t see anything under here, but up between the throttle body and oil filter housing there’s a black box with with hoses coming off of it.