If this was a widespread thing - and it would have to be for you to be running into it regularly - there would be people bragging online about doing it, posting videos of themselves doing it, and documenting how they do it.
You can find all of that with a simple Google search for videos of people using an engine, or hacking in online video games.
But you can't find a video or a credible claim of a disconnect hack in online chess. It just doesn't exist.
There is no army of super hackers that somehow can all take control of the chess.com live server and somehow see nothing more to be gained by that control than winning a small handful of games they would otherwise have lost.
I wonder why some players make such comments defending the site and being rather unsympathetic to the fact that happens to many, yet they defend the system and argue as if one who has experienced this is just making a false observation. I wonder if they are actual players or planted site defenders? or maybe the ones who know how this takes place! lol Any how I think there a bit more than coincidences specially when it only happens when one is winning and never when one is losing!
I've lost a couple of games due to abandonment when my connection or device was acting sketchy. I've had a number of games where I was certain I had disconnected, even though the client didn't reflect that, so I refreshed. None of those were caused by my opponents.
edit: actually, only lost one game by abandonment ....