99% sure the diagnosis is damage don't know of any error that would do that. The pic is a little distorted so I can be absolutely sure but logic and the actual possibilities exsisting say damage
Could be a Lamination error. (De-laminated) No big premium.. Those are common on wheat Cents. $1.00 - $2.00
That would be a cool lamination error, seems pretty unique, but u haven't seen to many, doesn't look like the one I have, it's from 42 I believe. Anyway, I hope you find good news, let me know what you find out.
I suspect this either a lamination or a strike through. I am thinking that the edges of the feature have been worn smooth so that it does not appear as quite what would be expected on either one. I think it is not damage because there appears to be no anvil effect on the Obverse.
There are a lot of metal groves/etches/grinding on the lower left going from the surface into the cavity along with the smooshing of the letters. You can see the remnants of the M actually being pushed up out of position. So I would think it's damage such as someone pushing a metal bearing onto it. Of course one would think the Obverse would have a convex section. Which it doesn't recognizably have, although maybe it raised certain areas that are thus worn away in the high spots you see ?? But I know nothing about lamination snafus ....
Here is mine, a 45 actually. Dig that 44 though, that coin has a certain loveliness to it you don't see every day.
I completely agree with Lamination/ delam. It is not uncommon to see the devices even to the center of the coin. IE in this case the A and M in a delamination. Here is one on the date If you look closely the 1 and 9 are still visible, also the lamination was over part of the bust and those areas are still visible.
The op's original coin in the opening post, a 1939 Lincoln Cent. Kinda looks like it's been buffed or slightly polidynow that I looked at it a third time.