https://www.ebay.com/itm/276695120522
Spotted this odd S mint mark on
ebay. The severe glare on the pictures makes it hard to conclude anything, and I wasn't $20 curious.
What drew my eye was the structured curved line under the S, and possibly through the S. It did not match any known RPM on VV or Wexler. That little connecting line between the stem tip and the torch makes me wonder if this isn't a polished out die clash remnant.
Of course, given the images, it could also be circulation or bag damage, die gouges, or any number of other things.