When US sellers use the Global Shipping Program through ebay its our safest, and least liable way of transacting with international buyers. Your essentially prepaying your customs and tax fees, its not really an “additional” l+ 20%. We as sellers only price in the shipping to the Kentucky GSP distribution center. So for example say its $5 to ship to the GSP center for me, Ebay then adds in their additional cost to ship from the GSP to you.

Per Ebay, Buyer charges:

In your listing, the buyer will see estimated shipping and import charges; the full and final charges will be available for them to view at checkout. They can also view what they've been charged on the Order details page.

The shipping charges the buyer sees include any US shipping charges that you specify, as well as international shipping, handling, and other fees

The import charges include any customs duties, taxes, brokerage, and other fees
You receive the item price and the domestic shipping and handling amount that you specified directly from your buyer

The gsp fee is separate from your “prepaid” import obligations I believe. Im not completely familiar with import fees and such but thats what are are told as sellers. Your best bet is to find a way to get them to message you on a different platform without getting caught. I like to write a Social media name of mine on a piece of paper and add the pic to a direct message to them. Make it barely legible or use symbols instead of letters, or even giving your forum name, be discreet with how your write and relay message through the picture your attaching to the dm. Its the only way that seems to bypass ebays “deals outside of platform” majority of the time. Just make sure you do your due diligence and use proper buying platform (paypal invoice is my go to) when doing so. Granted you aren't as protected as you are through ebay, but this helps sellers save on fees and usually leads to a much cheaper price for buyers

I think it only happens to listings being added. According to the forum thing on ebay, its been going on for a few weeks or so. 

Mine shows in the active items as 5k, but as soon as i go into it its priced at 6k. I called them yesterday and they have had loads of calls about it, and are working on a fix. 

It seems they have fixed it now. But you will have to relist things the bug over priced, it wont work if you try to revise them.

Edit, no they didnt! Mine did originally list at 5k, but now shows as 6k. Ill stop with the posts and just say watch your listings, something dam weird is going on at Ebay.