This mission was highly suspicious... Yuhara had formed this opinion the moment that Uchiha ninja was restrained.
First of all, according to the original arrangements, Yuhara and the others were supposed to be "off duty" on the day this Anbu team carried out its mission. In other words, it was supposed to be a free day, yet this mission had come extremely suddenly.
Secondly, a mission to act against a jōnin from the same village theoretically required the Hokage to issue the order personally. There absolutely should not have been a situation where an Anbu squad leader conveyed the order on his behalf. Otherwise, Konoha would have fallen into chaos long ago... Yuhara did not know what the standard procedure for accepting such a mission was, but it definitely was not what had happened earlier.
The three of them were newly inducted Anbu shinobi, which meant they did not understand the Anbu's internal operations. At the same time, becoming Anbu shinobi meant they were highly capable, and people like that could be used. One person dealing with a Uchiha jōnin and four people dealing with a Uchiha jōnin were completely different matters.
Third, once the mission was complete, the squad leader absolutely should not have handled the handover alone. That was the most suspicious point. Given the Anbu system's strictness, the squad accepted missions as a squad and handed them in as a squad. It was simply an unavoidable procedure. As long as the mission had not been handed in, it was still "in progress." Since it was "in progress," how could a squad leader possibly disband his own squad?
Based on Yuhara's covert tracking, although he did not know all of the Anbu's bases, he could be certain that the place where the squad leader handed over the mission