20 seconds before Evander Kane scored the backbreaker in the second period of game 1, he committed an obvious and dangerous crosscheck on Stone.

Not only should it have been a power play for the Golden Knights, but a) it caused the turnover that led to the goal and b) the guy who scored the goal 20 seconds later shouldn't have been on the ice because he should have been in the penalty box.

That said, I am at a loss trying to understand the interference rule.
The Golden Knights had several interference challenges this season that were far worse than that where they counted the goal. The NHL's interference rule is a complete mess.