Though the going narrative is that this break was "pre-planned," Alvin Bragg has every power to convene the jury whenever he chooses. If he was close to indicting Trump, he would, but he isn't and is stalling to save face. This alternative theory makes more sense since Trump only gains more political support the longer this witch hunt lags on. As Bragg keeps grasping at straws, the Democrats' chances of jailing Trump grow smaller and smaller.
While this decision is certainly unusual given the jury has already taken a hiatus, it's likely that Bragg is ensuring all his ducks are in a row before an indictment. Trump has been using social media to try and derail his fate for weeks. This is why Bragg is staying calm — he wants to make sure his approach is flawless.