it's ebay seller fees. They take a percentage of what you sell or sold recently, it will always change due to what price you sold the item for, if you cancelled a sale and mark it as sold when it did not, you will also get charged so be careful how you end a listing pre maturely, otherwise it's calculated on 10% of the amount of what you sold, thats what this is....it's part of the user seller agreement, you might want to check your ebay service agreement as it changed in order for them to do this back in late 2018...i would suggest if you have quite a large sum of money in your asking price on your item to expect a 10% deduction loss of that sale price,
This was changed by ebay to crack down on fake ebay accounts, as well as sellers offsetting their prices towards high postage costs ripping off buyers, now it's all included in the sale price both sale of the item and postage costs,
there is nothing you can do about it, it's in your ebay seller user agreement terms,
id suggest if you have put a low sale item price with an unrealistic postage cost ebay is no longer for you as you will now get charged and deducted on that high postal cost.
whatever you sell on ebay will be a 10% deduction fee calculated as a total of the item your selling along with its postage cost .
