Well that is what it says:

”Your tax information has been verified, and you’re now eligible to be paid through the Medium Partner Program.Starting in 2020, your Medium Partner Program payments are subject to international tax withholding of 30% based on your taxpayer information, which indicates your country for tax purposes is Denmark.“

But since I live in Denmark, I have anyway to pay another 40% Tax of the amount which they send here. So it will be even less :)