I hadn’t heard of brushing, but you might also be a bystander for a different common eBay scam. Seller sells to Buyer, but ships something different to another address with the same zip code. I think eBay may have since fixed part of this, but the deal was that all the tracking info would show that the seller shipped and delivered something of the right approximate weight to the buyer (because USPS would only share/confirm info accurate to zip code level).

The thing that makes it less likely is that the buyer and seller had multiple transactions together which is uncommon for eBay. And also if the stuff you got was expensive. Maybe buyer really just put the wrong address and neither side can do much to get the item back once delivered?

I got hit with that exact scam recently as a buyer, and I can tell you eBay has not figured out how to mitigate it yet. I purchased an expensive item from the seller. He sent some token thing to a different address in my city in the same zip code and provided me (and eBay) the tracking info. Item was delivered, and all eBay knows is "item sent to zip code X was delivered" so it was marked as delivered. I submitted a dispute, which was pretty much instantly closed with "Seller provided proof of delivery." I contacted UPS who happily provided me the actual address the package was delivered to. I escalated through eBay's support channel and offered to prove that the delivery was not to my address but they didn't care or want to know the actual delivery address. Finally, after a few days, eBay got back to me with a form letter saying I would be refunded because the seller's item was "lost in the mail," which was total bullshit, but at this point I didn't care since I got my money back, but the scammer probably kept the money too, so I guess eBay is eating these costs.