Epic had announced that Ticket to Ride, Carcassonne and Pandemic would be available as there weekly giveaways. They have just removed Pandemic from that list and it seems to be unlisted on the store as well now.
A suggestion is that the coronavirus has something to do with it.
It’s a game about finding cures for dreaded diseases! It’s not like you play a disease trying to wipe out humanity…
That said, it could be the game-maker / publisher itself asking for the game’s availability as a free title to be pushed back. Maybe they don’t want to appear opportunistic.
I see CCN is suggesting that Epic has removed Pandemic as a freebie to get people to spend money on epidemic-themed games. Deactivating Pandemic’s listing seems counter to that goal, though.