Danish banks have implemented significant restrictions on how Danish kroner (DKK) used outside Denmark can be repatriated back into Denmark.
Due to these circumstances, which are unfortunately beyond Mullvad’s control, Mullvad will no longer be able to accept DKK from its customers. We will continue to credit DKK received until the end of the month, but considering postal delays, it is best to stop sending it immediately.
There’s a lot more to sovereign monetary policy than currency exchange rates, such as the capital controls being exercised here
I was trying to find information about this restriction. It seems it applies to cash and relates to Danish banks’ ability to implement AML controls. https://www.nationalbanken.dk/en/what-we-do/notes-and-coins/exchange-of-danish-cash-abroad