Did you get your shipping quote from the Shipping and Payments tab of the listing on the full website (after making sure it is set to the zipcode of your intended shipping address)? I do not trust any other display of s/h quote, even the one at the top of the listing under the price. Other displays may be to the wrong location or otherwise inaccurate. Check the S&P tab now (click the link to see the "original listing" in the short-form completed listing page that comes up when you click the link to the listing in your Purchase History) to see what is the correct fee to your location (for the option you want to use if there are options).
If the listing does show free shipping to your location for the option you try to select at checkout, and the seller has issued an invoice with revised shipping that you did not request, you can appeal any unpaid item strike for the seller changing the terms, see https://www.ebay.com/help/buying/resolving-issues-sellers/appealing-unpaid-cancellation-record?id=43...
