WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 170, "A New Rasengan," now streaming on Crunchyroll.
The Boruto anime has created a major rift in the Uchiha household thanks to Sarada's current training regimen. She's pushing herself with Sasuke as she wants to overcome her weaknesses, but we soon discover that upgrading her skills is causing huge concerns from her mom, Sakura.
Despite the kids needing to improve to face the maniacal Deepa again, the former Team 7 shinobi and war hero from the Madara-Kaguya debacle believes the Mangekyo Sharingan her daughter's so desperate to achieve will hurt her more than it will help her in the long run.
This ocular power-up is both a blessing and a curse for the Uchiha family. It grants them immense power such as the Amaterasu flames and the Susanoo chakra golem, to the point they can be considered gods, but it comes at a hefty price -- they must first experience the death of a loved one. Itachi got his when Shisui took his own life; Obito got his watching Kakashi murder his beloved Rin, while Sasuke got his after Itachi died. In some cases, this also makes the wielders potential targets as it's believed Madara killed his brother, Izuna, for his eyes.
Tragedy clearly follows this manifestation and Sakura doesn't want Sarada trying to attain it because of this. Sakura thinks this blight will lead to either Sasuke or her death, or the death of one of her teammates such as Boruto or Mitsuki. To the medical ninja, whoever seeks this out is calling death to themselves and as Sasuke notes her prowess in training, Sakura can sense Sarada is rapidly approaching that point. Granted, no one can tell when it'll happen, so until that emotional moment, Sakura is going on her superstitious gut instinct and the legends of the past Uchiha, which Sasuke can corroborate.
Sadly, he knows that this upgrade turned most of them into villains, fueling their need for revenge against Konoha and other ninja nations and also encouraging them to seek out power as dictators. In that sense, Sakura knows it could tempt and corrupt her daughter if she ever becomes weak. This Sharingan evidently has a habit of damaging people's mental health, opening their minds to be consumed by darkness. Not to mention, overuse can make them blind as it was doing to Itachi, which places a strain on their psyche even more.
Notably, as Sarada has Sakura's blood in her and is a member of a diluted Uchiha bloodline, Sakura doesn't know what the side effects will be physically and mentally. Despite this unpredictability, Sakura wants to protect her, leading Sarada to feel enraged by the idea that her mom is holding her back. As the parents discuss the need for this apparently unnecessary upgrade in a time of peace and science, Sarada becomes even angrier. The maelstrom inside is pushing her towards this breaking point more and more; thus, by resisting the change, Sakura isn't helping, as this whirlwind of emotions will backfire if Sarada thinks her progress is being impeded.