Note that all the areas you are looking at is where the die flow lines are. This is just die flow on these fields. If it were a phantom 'D' the shape would be raised, not just flow lines. On an earlier die state, these would not be seen. It it were a RPM. it would be visible on earlier die states. Thus why the 1980-D-S coin that was debunked years later:

The earlier examples (same mintmark locations) didn't have this look on them. Thus they debunked it several years back.

The earlier examples (same mintmark locations) didn't have this look on them. Thus they debunked it several years back.





























