That's obviously a foul on Jaylen Brown while PJ Washington was trying to dunk the ball. He won't end up in the crowd without any reason. The referees can call it even if it's late as long as he blows his damn whistle.
Boston Celtics won the game but it's not that far. The two best closers of the Mavs did not work pretty well in 2nd half. But we are seeing some lobs now. Gafford was also aggressive inside the paint and scored using a post-up game. That's nice to see.
Against a hostile environment like the TD Garden, I think the Mavs still did well tonight but the defense of the Celtics is suffocating, they must find a way to break that.
Anyway, I didn't watch the 4th quarter because I had some errands to do, but referees when they play in TD Garden has been known for not calling obvious fouls. One example is the infamous Lakers-Celtics game where Tatum was obviously hit Le-GM's hand and didn't call a foul that would give them free throws. Even Beverley got a camera to show it at that time.
Well, the Celtics successfully defended their home court as they won against the Mavericks 105-98. Luka's triple-double isn't enough because Kyrie again only scored 16 points and shot 7/18 from the field which is better compared to Game 1. The game was close at least for the majority of the game (that I've watched). Other Mavericks' players helped with the offense, but I guess it wasn't enough for them to steal a game on the road. What's alarming for me is Tatum's performance in the first 2 games. Averaging 17 PPG in the first 2 games, and shooting only 12/38? You're a superstar of the team, and you're shooting like that? It's good that he has good teammates to cover his poor performance, but it's unacceptable. What if other players had a bad performance? I'm not a Celtics fan, but he's one of their reliable shooters, and he is shooting like that.
Anyway, I agree with what you said that the fans on the TD Garden really are very hostile to the opposing player that they even boo Kyrie whenever he gets the ball which might affect his performance at least. Now the next games will be on Mavs home which for me is way louder than that of Boston. Let's see how the Mavericks will play on their next 2 games.
Just for context, teams that win the first two games at home in the NBA Finals go on to win the series ~89-90% of the time.