Why is Qf5-c2+ a blunder? Wikipedia defines a blunder as follows:

In chess, a blunder is a very bad move. It is usually caused by some tactical oversight, whether from time trouble, overconfidence or carelessness.

Here when I use the engine from chess.com to analyse a game, the engine considers black's move Qf5-c2+ as a blunder and Qf5-h3 is considered as the best move. I failed to see why Qc2+ is a blunder; can anyone help me to explain?

By the way, is this game a draw before Qf5-c2+ (assuming both sides make best moves)?

Edit: I am still curious about this position; anyone can help me with a deep engine analysis and see if it is a draw?
The engine considers Qc2+ a blunder because it's a draw by repetition. (I think the position is probably a draw anyway, but Black could at least try for a win.) The problem is that you have already reached this position twice before. If this was the first time you had reached this position, there would be no problem: Qc2+ is actually a good move in itself. But since you have kept repeating the position instead of making progress, you now need to play something different, such as Qh3.