Ranked bug?

I just saw a guy in custom game who was lvl 1 and challenger in TFT with only 80games (20wins - 60losses-? How the hell? I checked him out on tracker.gg for his stats and he somehow jumped super hard between ranks... I'm quite new to TFT , recently started playing it and don't play ranked only normals so IDK how it works, but is this normal? https://imgur.com/AXdVFGa