The only experience I have of this is every bookie I use (online) have a suspended marker when a goal goes in so you can’t bet on something that is affected by VAR. They essentially stop you from betting on the game.
for what I have seen (last match was Braga vs Famelicao Portuguese League) with betfair exchange you can bet while referee is making the decision (watching replay) since the odds are adapted by the players.
isn't a bad option take advantage of these situations. But there is always the risk of a negative evaluation, VAR doesn't means it's a no risk bet.
Yes, this is the problem. I noticed this problem by multiple bookmakers. So I am very curious how they deal with this. As some users already mentioned, Bookmakers, can use the rule in their favor if they really want. And if the bet is not in their favor, they can decide to cancel the bet. In such cases it is only a win-win situation for bookmakers. Bookmakers are giving odds for the match a few seconds after the goal has been scored. Then the odds are blocked again, but in these few seconds a user has the option to place his bet. Not all bookmakers are using this. Some bookmakers block the odds from the begin to the end, until the decision is final.