Yesterday I have sold and item that was region locked to Europe. The buyer is from America. The region lock was clearly stated in the title of the offer and withing product description.
What is the usual process here? The buyer now has my key and can probably sell it/send it to anyone anywhere.
If you clearly specified in the listing details that the product is region-locked as you’ve mentioned, the dispute should be ruled in your favor. I’d contact support just in case.
Usually in cases like these, support will favor the dispute to the seller and the buyer will be instructed on how to resell the product on the marketplace.