Yes they will report and send you a 1099k but for personal items you most likely bought it for a similar price or maybe even more so no gain, no tax.
Notice how Amazon and Ebay now charge the buyer sales tax?
This was not the case before but stems from the Wayfair vs south Dakota ruling in 2018.
For sites that do not collect sales tax I imagine states could use this form to collect thier share.
AND you will pay sales tax always but only the buyer pays.
That's where this new ruling will get it's money.
Imagine paying 8% more for everything you buy on Agon?