No active seller account, but Amazon Marketplace charging me $1.75/month

I sold a few items on Amazon waaay back, like probably 15-20 years ago. (Sorry, I’m a bit vague on the timeline of this whole saga as I never thought it would matter.) Then maybe 5-10 years ago, they notified me that my seller account was being terminated due to alleged fraud. I hadn’t done anything fraudulent, and in fact hadn’t logged into the account in years at that point. I believe I did send an indignant inquiry at the time and basically got the response that there was no possible appeal and their decision was final. Obviously I wasn’t any sort of serious seller, so I just let it go.

Fast forward to now and I notice this charge on my credit card (a Prime Visa, if it matters): PLAN FEE – AMAZON MKTPL*N. The charge is $1.75/month and it started in June of this year. As far as I can find online, a charge that shows up that way could only be a seller fee, except the monthly one charged to pro sellers is $39.99 whereas individual sellers are charged $0.99 per item sold, not per month. Obviously I’m not selling anything at all, so either way I’m confused.

My Amazon customer account is now associated with a different email address than the one that was associated with the old, allegedly terminated seller account. If I try logging into Seller Central with the old address, it says there is no such account (good, expected); with the new address it lets me log in and offers to help me set up a seller account, so no indication that they’re already charging me or why.

I sent an inquiry through Seller Central Help, but I have a feeling this isn’t going to be an easy one to solve. Has anyone encountered or heard of a $1.75 monthly Marketplace fee?! I have a screenshot of the CC transactions, will post it in comments if that’s allowed here.