22 hundred in classical - 25 hundred in blitz OTB

Someone told me in a chess club that one of the guys were playing grandmaster strength in blitz 25 hundred something, so I thought wow he must be a grandmaster then, on which I received quite shocking answer, that the guy only around 22 hundred player barely a master. I asked how this is possible and they explained it to me that this guy practices blitz all the time as a main play, that's why he's so good at it.

My question is, is this possible? I mean playing grandmaster strength or just strong play and very weak classical play is this possible?

Say the guy 1800 in blitz and 1300 in classical for example , something like that you got my point

🤔

Very confusing