This is true and also something we eventually get used to I think.
I've seen the same flow happening IRL, where people new to the team expected a somewhat responsive crowd when they present, just to be met with a wall of laptop screens and inscrutable faces when the time comes.
To be clear the people in the room were paying attention, and effectively cross checking info and exploring the points they wanted to focus on. They just didn't give any feedback to the presenter until the end of the presentation, when it's time to discuss the details.
It can be seen as socially rude, but to us it was really efficient: instead of telling the presenter we'll give feedback another time, at the end of the presentation we already had a rough opinion with a modicum of confidence in the numbers or facts to discuss. Doing all of that checking before the meeting is another way to do it, but honestly I'm not sure it's much better.