This is rare, but I think it's something to do with the game desyncing and then syncing. I was playing a game with my friend and he told me I picked some complete different characters from the ones I pick, example, I had Claw Iori and he was seen Mai.
In my screen I could see his team but I beat it with no problem, then he told me he won on his screen and I won on mine, but he saw different characters.
So most likely this was a desync issue, but minimal.