Remove the cover plate to expose the wiring and take another picture.

Here’s the back side

How old is the home? Maybe a hardwired phone box? Or cable? Although those had round holes.

1968 but the weird thing is that there are 2 more a few spaces away and similar ones in the basement like you can snap in some kind of recessed lights.

Its an old school mono point adapter for track lighting, its actually almost made the same today.

you can put a regular powersupply

Are they all on the ceilings? I think you probably answered your own question--some kind of snap in light fixture. Sorta' like track lighting? Do you have any mystery/ unexplained wall light switches?

Any chance that you can contact the previous home owner & ask them?

Awesome thank you for the answer now I can shop for new covers

RL Relocation solved the mystery--thanks!

The Track Lighting Monopoint Accessory from Lithonia Lighting allows you to wire a single track head to a junction box. Once installed, you can aim the track head for directional light making it perfect for accent lighting.

Yes this was before the more common Halo style of track, slightly different connection style but they are still made, I know you dont want to, but if you cleaned those things up, L style fixtures would probably still clip in lol.

But either way you just have black and white wire plus ground so you can put in a regular junction box.