I've been on the trading card market for a little while now and I have noticed this message below pop up a few times. I've been trying to work out what it's all about. The most plausible idea so far is that the nation selling the card has CTE'd. As when a card is on the market you can't junk it or gift it. Though there is one problem with the idea and that is I can remember seeing one of my own nations getting that message because it said "you" before the other part.
"Could no longer offer card for 20.00"
Example