In a show where the plot resolved around battle, in the first seasons, she is useless. She does virtually nothing to help Team 7 and just stays in the background, letting others do the work. She even admitted this to herself. She was effectively useless in that season.
I’m Shippuden, it’s fair to argue she was useful, but it was her off screen action. I give her credit for holding her own against Sasuri, but she still almost died when fighting. She possesses Ninjutsu in Medical, and not in Fighting. She can hold her own due to her immense strength, which overall drains her energy and leaves her weak in the first place. The rest of the time, she doesn’t have any major fights in any filler or big plot besides the war, which she barely does fight, but has key moments. The show revolves around the others, hence making her an useless character. The only one I argue is more useless is TenTen, and there is no arguing she IS the most useless. Does nothing is both series and that showed in Boruto.
To be fair to Sakura, when your team is someone who is the Hokage and one of the strongest ninja ever, someone who possesses the Rinnegan, the competition can outshine. It would be much better if she were on a team with another. Eg: Kiba. I bet she would shine with that team