It is recommended to use PayPal Goods and Services when paying for an item. There are no buyer protections when sending PayPal Friends and Family, Zelle, Google Pay, Venmo, CashApp, Crypto, among others.
Same boat here. I used to own 1 rack of these gray 100s for a few months to a year or so, but I sold them a few years ago as well. I don't remember who.