I got banned a month ago with the same situation - trying to sell niche electronics and servers (neither expensive nor something you'd typically associate with any kind of scam). Did you list any items as local pickup only? Due to the bulkiness of the items I did so and I wonder if there's some scam we're not aware of that causes them to auto-ban anything with local collection only?

I since sold the items on a different website but will be making a GDPR DSAR to 1) get the data they hold about me (to see if there's anything that would explain the ban) and 2) to request a manual review of what must've been an automated decision.