When synchronising a product, the module always sends eBay information about the tax rate in use based on the default tax group set in the product sent from the site,
The only case in which no information is sent is the case “No tax”.
For this to happen, of course, the option “Prices including taxes” must be enabled in the general configurations of the module.

Starting with version 6.5.0, the possibility of forcing a dedicated tax rate by bypassing Prestashop’s options on a given marketplace is included: