Not defending eBay but in some cases there is not much they can do. There are a number of possibilities as to what has happened here. First separate the 1099 issue from the account issue they may or may not be connected. The 1099 is not a form saying you have to "pay taxes" it simply reports funds that were processed through a third party financial processor. Review the 1099 do the last 4 digits of the SSN match yours? Is the payee information correct as far as your name, address, etc? What is the amount processed on the 1099? I am not sure what state you are in but other than a few states the current 1099-K issuance threshold is $20,000 so we are talking a significant number of transactions over the last year. If there are issues with the 1099 contact the IRS at 1-800-829-1040. If the "hackers" have your SSN and are using it on another account you have bigger problems.
Pull the transaction report for your account for the year, if it is this account you are referring to I see little activity as far as sold items in the last 3 months and there are only a couple of feedbacks related to items you possibly sold recently. If the detailed transaction report for 2023, which would be the tax year for which you probably received the 1099, shows the sale of a large number of items from this account the detailed report contains shipping information that could possibly track down the origin of the shipment and follow the shipping trail. You can also look at the money trail for this account. What banking information is this account attached to? Is it an account you actually have?
My guess, lacking additional information, that your account has not been "hacked" but you are the victim of identity theft.
