The drawbacks could be many. Firstly, using this ability might require a great deal of concentration. In the heat of battle, it could be hard for Naruto to focus on controlling blood while also fending off attacks. Secondly, there could be a limit to how much blood he can control at once. If he overextends himself, he could become weak or even pass out. And finally, enemies might find ways to counter this ability, like wearing special suits or using jutsus that disrupt blood control.
One potential drawback could be the moral implications. Controlling someone else's blood is a very invasive and potentially cruel ability. Naruto, who is known for his kind heart, might struggle with using such a power. Also, it might be difficult to control precisely, and he could accidentally harm allies if he's not careful.
There are several potential drawbacks. Since blood is a vital part of the body, Naruto might accidentally cause fatal harm even when he doesn't intend to. This could lead to him being feared by others. Also, this ability might attract unwanted attention from very powerful and evil forces who would want to either use him or destroy him. Additionally, if he depends too much on this blood - controlling ability, he might neglect to develop his other ninja skills, which could put him at a disadvantage in battles where blood control is not effective.