Ever since becoming the Three-Eyed Raven, Bran has become incredibly blunt, and often just sits around talking about how they don't have time for anything, because the Night King is coming. So when the show's big bad showed up on Winterfell's doorstep, everyone was poised for Bran/Three-Eyed Raven to pull some serious moves. Instead, in classic Bran fashion, he immediately warged into ravens and presumably spent the battle flying around. All the while, the Iron Born died in the Godswood protecting him. It's unclear if he was doing something aside from being ravens—which, we'll add, would have had just as much purpose to the episode had they not been Bran-warged—but it wasn't a great look for the guy to just sit under a try while thousands died around him.