I have had that problem before months ago (on my old account which I removed).
It was on the android app. I dc'ed, returned within 30 seconds, and I couldn't find my game (10|0 game). When I looked at the game in my history, it said 'x won by resignation', aka according to the game I resigned while I cannot recall that I actually did resign. It only happened sporadically, so I never bothered reporting it.
Although I do not have a solution for you, just sharing my experience :)
few weeks ago, I unfairly lose a game becauae of a theoretical resignation which never took place, and again its happening I had a great network conection(3'5G) and I was winning when suddenly happenen de same. what shall I do??? regards:Eduard I have taken few screenshots