Multiplier certificates were in such high demand that their prices have seriously increased.
You are not logged in. You can continue playing without logging in, but until you do, your game data will exist only in RAM, lasting a day at most, to remind us that all states of matter and energy are temporary.
If you log in or create a new account, you can permanently save your high scores, achievements and unlock points, proceed further in the game, and hide this dumb notice.
Well, by "Permanently," I mean "I'll put it on the hard drive." Nothing is truly permanent.