Kakashi not telling Sakura and Sasuke about Naruto being a jinchuriki is a major problem to the team's unity and teamwork. At some point, Kakashi should have informed both Sasuke and Sakura that Naruto was the Ninetails jinchuriki and their teammate had a demon fox sealed inside him.

I can understand concerns that doing so might create a rift between the team, and for this reason I understand why Kakashi might not tell his team Naruto's secret right away, allowing the kids to hash out friendships and establish team camaraderie before revealing that Naruto has a frightening power sealed away in him. So for D-rank missions, that's not a big deal, but as soon as the team started facing regular conflict and going on higher-level missions, Kakashi needed to spill the beans.

That Kakashi never told Sasuke and Sakura about Naruto's "problem" is a hazard, since Naruto doesn't even have full control of the Ninetails, meaning it's not impossible that he could go berserk at any moment. The secrecy on the subject was incredibly careless, particularly in situations where Kakashi sent the three genin alone on missions without him supervising.

Naruto keeping such a major secret was already damaging to the team's unity. Comrades can't fully have effective teamwork when they're hiding major secrets from each other, and Naruto's failure to tell his teammates his secret speaks to lack of trust in his team, which damages a team's ability to stick together and trust one another.

Kakashi could've fixed this by privately informing Sasuke and Sakura of Naruto's Ninetails secret. That way, should Naruto ever lose control, Sasuke and Sakura know what's going on and can react accordingly.

It would also help them understand Naruto's power, which might make them less afraid of it, because at least they'd know what they are dealing with and what to expect.

As is, Sasuke was already somewhat scared of Naruto due to witnessing on occasion a terrifying power that he didn't understand. Sasuke was unsure of how Naruto accrued such enormous power, which led to Sasuke feeling scared of his teammate and uneasy about Naruto. And you do not ever want teammates to be scared of each other. This fear could have been cleared up had Kakashi just outright explained it to his students.

Kakashi especially should have brought up the Ninetails power to his team after the Akatsuki revealed their intentions to capture Naruto, because so long as Naruto was a target, Sasuke and Sakura were going to have to deal with that danger as well so long as they are all members of Team 7.

Kakashi makes the exact same mistake again with Sasuke's curse mark. Sakura knew some things about the curse mark, but not everything, yet Kakashi never bothered to fill her in. Even worse is that Naruto was completely in the dark about Sasuke's strange mark the entire time, and it's Sakura who has to tell Naruto about it, not Kakashi.

The fact that the whole team is always sneaking behind each other's back and keep huge secrets from each other is majorly problematic and a barrier to effective teamwork, which is based on trust. Sasuke's curse mark was as much as a lose canon as Naruto's Kyubi, and seemingly more so in Part I. Yet Kakashi was just going to allow Sasuke to continue working normally on a team with Naruto and Sakura, even after Anko warned him about the danger the curse mark posed to Sasuke and even while Kakashi had no idea if the curse mark could take over Sasuke again at any time, making Sasuke a dangerous threat that could hurt Naruto and Sakura at any time.

The whole situation was a dangerous mess and most impudent on Kakashi's part. It again shows how bad of a teacher Kakashi is. Instead of encouraging teamwork, Kakashi fostered an atmosphere of teammates keeping secrets from one another and being secretively hush-hush about crucial information that the whole squad needed to know about each other. I understand trying to let the kids hash out their friendships with each other on their own terms, but that should never apply when the team's lives are at risk.

Besides, as team leader, Kakashi should be aware of the chemistry of his team and mediate when needed, and act to alleviate and remove misunderstandings when necessary. The curse mark and the Ninetails are no joke, and Kakashi should have never taken them so lightly by neglecting to warn the whole team about them. Kakashi needed to make sure each of the trio were as informed about the dangers they faced as a team, not segment them off as individual problems that didn't involve the rest of the group.

Additionally, Kakashi should have had a contingency plan in place in case Naruto's or Sasuke's abilities went haywire, much like how in Boruto, Doshu and Tsuru were taught and equipped to deal with their teammate Enko's difficult-to-control secret technique whenever it acted up and became dangerous, both to protect themselves and their teammate.

It also wouldn't hurt for Kakashi to take Naruto and Sakura aside and explain Sasuke's past to them and tell them both how Sasuke's brother had betrayed him and murdered his parents and clan. Ideally Sasuke would eventually tell Naruto and Sakura about his past himself. But in the meantime, that's an important part of Sasuke that might be beneficial for Sasuke's teammates to know about, that way they know what he's going through and what they're dealing with and how to interact with their teammate when broaching certain delicate topics like his past, his clan, or family.

After all, that's what Minato did with Obito by telling him Kakashi's backstory and it did wonders to improve and deepen the team's unity and friendship. Kakashi and Obito practically weren't even friends until Minato told Obito the story of Kakashi's past. Considering how important and impactful Obito's praise of Sakumo was to Kakashi, you'd think that Kakashi might understand better than most how important it is to have friends who are aware of your background.

Kakashi knows more about his students' individual backgrounds than they do about each other, so it should be Kakashi's job to mediate and provide information as needed to encourage camaraderie and strengthen team friendships.