At 14:50 of the second period in the Golden Knights/Islanders game, Vegas requested a Coach's Challenge to review whether an Islanders player interfered with Vegas goaltender Oscar Dansk prior to John Tavares' goal.
After reviewing all available replays and consulting with NHL Hockey Operations staff, the Referee confirmed no goaltender interference infractions occurred before the puck crossed the goal line.

Therefore the original call stands - good goal New York Islanders.
Since the Coach's Challenge did not result in the original call being overturned, the Vegas Golden Knights forfeit their time-out.