you lost connection on their turn... so when they make a move you are losing on time and when you reconnect it reflects that..
you lost connection so the server didn't have the ability to tell your computer that he made his move and now your time is draining but on your screen it seems as if he never made another move and loses on time.
what happens if you win on time but someone turns off the internet well nothing is supposed to. so why when i reconnect it says i lost on time and deducts rating points for absolutely no reason? sorry chess.com but i had to point out this flaw