Your issue is described here: Endless turn, Card Stuck Hovering, and Never Roping
You disconnected. The match is long over. Your opponent had to wait a minute or so and then got the “your opponent left” message and a win.
If this happens again in the future, force-quit (Alt-F4) the game as soon as you notice, restart, and wait for it to reconnect. If you are fast enough you might not even lost a turn. If you are slightly slower you lose a turn but at least still have a chance to recover.