Earlier I wrote that I was receiving many small, suspicious donations. I notified PayPal about the issue, but unfortunately I only got a form-letter response back (and it took a week to get it). I refunded every single suspicious donation, and was getting worried that the refunding would then flag me as some participant. So I started including comments in the refunds to notify the individual that I had reported the activity to PayPal and to STOP IT. There was no “please” or politeness in my wording, but there were also no accusations or anything.
Finally, today I got an e-mail directly from the individual.
Definitely no more such donations.
Hopefully that means it is done. I don’t know if the individual was actually trying to send me small donations and did not understand that PayPal takes 100% until you reach about 35 cents, or if it was an attempt at gaming or fraudulent activity. As long as this is the end of it, I consider this case to be closed.