Why do some players when loosing will act normal, the. Ask for rematch and if by chance they win it, will start spamming oops?

I am a dojo level 9 player, I rarely use ling as I use mainly shang and Azuma, I fought a guy with my level 7 ling. He was dojo level 7 and was using kibo of level 8.

As I said I rarely use Ling. So, I lost the first match, nothing happened, then Asked for rematch, and won the second match, used kate salute emote(I always use Azuma's cap down or Kate's Salute, or if the opponent uses Ling's thumbs up, I do the same). Then He asked for rematch, and he won the 3rd match. We both together used Kate's salute emote. Then I don't know why he began spamming oops immediately. Did I do something wrong?