Any idea how old this holder is? Aren't PCI holders known for sometimes toning coins in interesting/unusual colors? Edit: possibly that just applies to older generation holders...
Based on what I found this generation of PCI holders was from the early 2010s. There is an older style that has a different look to the label that is known for toning coins in the holder. I can't remember whether it is the blue or green border off the top of my head, though.
I found this previous thread that gets into the differences in the green PCI slab versions: https://www.cointalk.com/threads/toned-morgan-in-pci-slab.397361/
I also have been collecting 1881-S Morgan dollars. I have many in all the different PCGS holder and many in the ANACS photo certs, PCI, AGC, INGS Photo cert, and many out of business holders.
It is a fun way to collect as I love Morgan’s and the strike is hard to beat on the 81-S. I also love the history of our hobby and older slabs intrigue me. Mike