Any idea what this is? Found in engine air filter

[WNC Forester]

I found this small rubber black cap with foam insert *I think* inside of the engine filter element compartment (or maybe I knocked it off from somewhere in the filter vicinity) when I was replacing the filter. Any ideas if it came from the 2021 Forester engine or maybe from equipment used in a prior service? Thank you for any advice! John

 

[NotADuck]

I've only ever seen these covering 'unused' holes (generally that are blocked off anyway). I suspect they're simply to keep out minute amounts of dust/dirt. I'd have a look around the vicinity to see if you can find any more that could give you an idea of what it covers. Personally, I wouldn't be very concerned, but that's me!