Maybe fungus, do you spray. When do you fertilize? Container or ground?

Any pollinators in the area?

Have you cut into any of the spotted apples?

If there weren't any pollinators, there wouldn't be any baby apples so you can eliminate that concern :-)

But I do agree you need to cut a few of these open. And do so through or right next to the spot. There are various flying insects that will lay their eggs on tiny emerging fruits and their larvae then tunnels into the fruit to feed and develop. But you need to see and identify them before you can apply any effective controls.

I haven’t sprayed the apples with anything In recent years. Here is a cross section. I can’t discern any eggs or larvae.

triazicide "Once and Done." apply after petal fall and again 4-5 weeks later. I have about 75 apple trees in MN Zone 4 and I have no bugs in my apples. Big box stores don't have it, get it on line.