News outlets are, in general, extremely conservative when calling races. The usual standard is somewhere between "there are not enough outstanding votes to change the outcome" and "the uncounted votes have to be insanely different to anything likely based on previous elections". More [1].
Changing a projection has happened but it's incredibly rare.
[1]: https://www.reuters.com/business/media-telecom/how-us-news-o...
Like, it's an extremely weird system, but it is how it has always worked. If you refuse to use it, you won't have a result for weeks.
NBC's last two projection errors were 2000 (Bush v Gore presidential race in Florida, which was universally just a fucked race) and 1960.
It is a given at this point that Democrats have, in fact, won control of the House for 2027 (as long as there isn't any Trump shitfuckery, which I think the win this year is going to be way too big for him to even try it).
The former wasn't an error. So they've made one, 60 years ago.
To be clear, I'd love it to be true, but I don't think we should be reporting things as fact without a mathematical certainty or a concession.
Democrats win control of the House of Representatives, with a vow to combat Trump
NBC News projects that Democrats will take control of the House next year, giving them the power to investigate Trump and advance legislation to check his policies.