[john70t]

https://www.reddit.com/r/Flipping/comments/rjdonb/5_way_ebay_screws_over_sellers/?rdt=45459

The thread got archived aka memory-holed: https://community.ebay.com/t5/Selling-Q-A/Do-you-think-Ebay-screws-sellers/qaq-p/24062717
This thread is pretty close to your experience: https://community.ebay.com/t5/Selling-Q-A/EBay-Screws-Over-Another-Seller-On-A-Return-That-Was-Never/qaq-p/31780831?nobounce

Here is a fraud tutorial: How to Screw Top Sellers Over on eBay https://www.youtube.com/watch?v=F4cva7oSgIc

My understanding is that Ebay tends to bias towards the customer in disputes.