I have this exact same thing under my eyes! It’s been like that since I was a teenager. I’ve tried to research it a bunch of times but everything that comes up (milia, keratosis pillaris) is not right.
I finally found one old Sephora forum post where the consensus is that these are just naturally enlarged pores, and that the cause is likely genetic — not caused by products or environment.
I think that means that there’s no perfect treatment that will get rid of them completely, but good hydration and a solid skincare routine might help minimize their appearance. Maybe try avoiding heavy creams and oils on that area as it might exacerbate their size.
It sucks to feel powerless, but also just remember that NO ONE looks at our skin as closely as we do — that usually makes me feel better!