WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 225, "Showdown Between Best Friends," now streaming on Crunchyroll.
Kawaki hasn't been an easy individual to deal with in Boruto. He's been rude to everyone in Konoha, hating on shinobi training and simply coming off ungrateful for everything the Hidden Leaf has done for him since he got liberated from Kara's grip. Ironically, the anime just saw him experience a rude awakening in the form of a deadly new rivalry - one that pays tribute to a famous Naruto feud.
While watching the Chūnin Exams, Kawaki got bored as he didn't care to be a ninja, nor did he want to watch the ambitious teens and learn from their experiences. Naruto begged him to do so as it would prepare him for when his time came, but the sulking, broody Kawaki left. Part of it was due to him being more powerful than the others, but a major factor in ignoring the Hokage was because Kawaki remained unsure if he wants to be part of Konoha's family.
However, as Kawaki exited into the fields, he was accosted by none other than Shinki, Gaara's adopted son. Shinki had been eyeing the teen for the whole duration, not even letting his team know what he was up to. Shockingly, he ordered Kawaki back to the games as he felt the kid needed to see how the Konoha-nin was developing. It felt a bit arrogant as Shinki was a guest, representing Sunagakure and the Village Hidden in the Sand, which led to Kawaki mutating his arm to attack.
Shinki quickly used his Iron Sand to form a shield, easily blocking and absorbing the blow. He then used the Earth, Wind and Magnetic Release techniques to create another arm to grab Kawaki, which ended with him restraining the rogue and slamming him into the ground like a petulant child. Shinki then repeated his request for Kawaki to get back to the contest so he could learn, walking off in victory. Later, when Shinki's team convened, he revealed his mission was not to monitor the exams, but to spy on Kawaki as his leader and Naruto's now-friend, Gaara, was concerned over Kawaki being an uncontrollable WMD.
It harkened back to when Sasuke first met Gaara, who intimidated him after Gaara's siblings ran afoul of Konohamaru, Naruto and Sakura. There were intense stare-downs and cold-one liners, just like what happened here in Boruto -- where, ironically, Kawaki cut a similar insolent figure to Sasuke.
But in Kawaki's case, he was more rash in his first encounter to fight and got resoundingly embarrassed. This also paid tribute to when Gaara and Naruto first had it out, with Naruto having to defend an infected Sasuke from being killed by the villain at the time. Gaara, with the One Tail, lost control with his Sand Spirit, forming a shield just like Shinki. He then pummeled Sasuke and Naruto, but thankfully the latter and his Nine Tails, Kurama, would counter and take Gaara out. This bout altered all their destinies as Gaara would shed his hasty ways and side with Naruto through thick and thin.
That said, it's easy to see the spiritual connection between the Naruto and Boruto eras with Shinki being a teen of few words. Gaara was the same way and just as he left Naruto and Sasuke petrified, Shinki had Kawaki feeling very weak and minor at the end of this short scrap.