Actually, there has been a version of that explanation available on the older forums for years. Now, is it possible that there is an exploit which forces people to disconnect? Yes, since those bugs have been found before, though typically this gets known by the community VERY fast, people who use it on purpose get suspended or banned and a fix is released ASAP.
One thing to keep in mind: this situation struck you because you were about to win. Everybody who complains about a disconnect like this is saying their opponent was about to loose. Nobody is complaining that the opponent was about to win, and I think the reason is that if one’s opponent is about to win, and it looks like they are BMing by holding the card, we just close the app or something to end it sooner, and don’t realize it is the same.
All that being said, if you think the opponent might have found an exploit, gather as much data as possible, minimum: all cards in play, all cards played in the last turn. Ideally also timing (with a video recording). And if it looks like a reproducible issue, DO NOT SHARE IT publicly! Instead, hacks can be reported here: