Seems like eBay is collecting sales tax for eBay.

As far as I know, sellers must only collect sales tax from buyers that reside in a state where the seller has a nexus.

For example, I sell on eBay and GunBroker as a side job.  I only charge sales tax to buyers that live in my state.  When I started doing this about a year ago that's what everything I could find said to do.