It says I lost by leaving the game

I was playing this game and was about to play the next move when suddenly it showed White is victorious Black left the game.
Why did this happen? I didn't leave the game

connection problems ?

I don't think so, but still, there is a time of about 30 seconds.
I was just browsing on the other tabs

This looks similar to this problem that was introduced today and will be fixed tomorrow: github.com/ornicar/lila/issues/5651