Game lost by abandonment almost instantly after opponent check

I lost my game by abandonment almost instantly after my opponent checked me. I'm really confused how it said my game was "abandoned.". I reported the guy for cheating, because I never seen this happen before. Is this a bug? What exactly happened?

Game: https://www.chess.com/live/game/5285389646

Your opponent can't impact your connection or disconnect you. The clients never connect so they never see your connection details. All traffic is handled through the Live server process.

You most likely got disconnected: https://support.chess.com/article/213-how-do-i-fix-my-disconnect-lag-issues

https://support.chess.com/article/338-how-does-game-abandonment-work

If what you are saying is most likely the case, wouldn't there be a disconnection timer at my part? I know when someone disconnects, the timer goes blinking and a message will pop up in chat. Neither of these happened to me. It was in an instant out of nowhere, that's why I'm confused.

It is possible for the client code not to realize you're disconnected. It doesn't happen often but I have seen it happen.