Is This A Error On Reverse Side Of This 1977-D Lincoln Penny?

I think you have a normal coin with a stain of some kind. Acetone and possibly a q-tip would remove it. Keep hunting!

And Bobby131313 is saying that the stain will dissolve and disappear. Not the coin.

So I just got home and looked at it does feel slightly raised I tried the acetone still their

Thanks for removing the coin from the 2x2. The last images of IGWT look to be MD.

Neat coin-
Some possibilities come to mind for the reverse (but I can't really tell from the images).

-Double struck and rotated (Nothing on the obv though)
OR
-A die event since it is raised (Counterclash?).
OR
-Struck through a very very late-stage die cap? (This is usually on the hammer die/obv during these years aren't they)

I whatever it is it don't come off

Stain often affects the coin longer on the lower areas. On the upper higher devices, the coin wear can remove the stain there, leaving the protected other areas showing the stain. Send on die scratches we see this. The highest points will show where the crack has worn off of the coin. The protected area will still show the die crack.