It was a 30+5 game in the Caro Kann, one of the easiest openings to get a very high accuracy(at least in a lot of lines).
I have many similar Caro(but from the black side) blitz games where my opponent plays the advance, plays some passive line, I get some queenside initiative and just play pretty natural moves, he drops a pawn or two and ez 90+% accuracy. Now if you looked at my QID/Nimzo games it's a whole different story.
Though then again taking with the bishop seems strange too. All in all I don't think it's super likely they either did/didn't cheat