Site keeps reversing time and moves

Recently, my moves are reversed and generous chunks of time are deducted from my time on the game and not the opponents. Is this a bug? Or is this a cheating technique? Or something else?
Thanks.

See lichess.org/lag

This can't possibly be just lag. I just lost a game where I had more than 2 minutes on my clock, but didn't receive notification that my opponent had moved, and so I timed out.

your internet timed out then