Time delay after losing important piece?

It so unethical to do it.

Like when you play a 10min game and you win an important piece. Then the opponent will not move for 7 minutes and you really waste time sitting there waiting. The worst is they move in the final 20sec and you didn't notice and you lose because of that

I wouldn't say it's unethical, it's just toxic. You should report those people for stalling in game

Its only  10 minutes.

 Someone walked off with 18 minutes on their clock against me... and didn't come back.. I sat there looking at my winning position and just gloated..  I might be a bit odd but I get pleasure out of looking at my winning positions.  But report them by all means...