Yoda was the Jedi of the Jedi Order, yet even he felt the dark side's pull during the Clone Wars, which he admitted during a brief scene in Star Wars Rebels. The Jedi and Sith are both orders that follow the light and dark sides of the Force, respectively, but there are other people out there who don't believe in their religions. So there are plenty of Force wielders who may toe the line between practicing the light and dark sides of the Force without really knowing the consequences of their actions.
Using the light side of the Force provides a more altruistic existence, whereas the dark side of the Force produces quick results but without any substance. Furthermore, it's easier for people to fall down the path towards the dark side, which is what Yoda told Anakin Skywalker when they first met in the High Council's chamber in Star Wars: Episode I - The Phantom Menace. He said, "Fear is the path to the dark side. Fear leads to anger. Anger leads to hate. Hate leads to suffering. I sense much fear in you." Anakin left the only home he ever knew, and although he believed he'd see his mother again, he couldn't be sure of that. But years later, that level of fear would also echo through other Jedi during the Clone Wars.
The Jedi were criticized by many, including Luke Skywalker, for their hubris during the war. Their ignorance made them blind to Palpatine's plans and his takeover of the Republic, transforming it into the Empire. And so, the Jedi became all but extinct as a result. But what's interesting is that Yoda admitted to being fearful and feeling something dark brewing in the shadows during the Clone Wars. In Star Wars Rebels season 2, episode 18, "Shroud of Darkness", he appeared to Ezra Bridger inside the Jedi Temple on Lothal and said, "Padawan, thousands of Jedi once there were. Then came war. In our arrogance, join the conflict swiftly we did. Fear, anger, hate. Consumed by the dark side the Jedi were. ... A long time, fought I did. Consumed by fear I was, though see it I did not."
Ezra was surprised that someone as revered and powerful as Master Yoda could also feel fear, and so abundantly without knowing it. But Yoda admitted not being wholly consumed by the fear and turning it into anger was a challenge all Jedi would face, and for life. Even Luke Skywalker said that "confronting fear is the destiny of a Jedi" in Star Wars: The Rise of Skywalker. Yoda and the Jedi Order were unquestionably compromised during the Clone Wars since they could not see that the person in front of them was the Sith Lord they had been chasing. But beyond that, it's not too surprising that Yoda himself would admit to such a failure.
Yoda's wisdom has always been unmatched; he continued to give Luke advice long after he had passed away, which fans saw in Star Wars: The Last Jedi. Yoda was willing to let everything burn, even the ancient Jedi texts, because those books weren't what truly differentiated the Jedi from the Sith. Luke finally understood that in The Rise of Skywalker when he talked about fear and the Jedi's destiny, because he, too, was once consumed by fear in Return of the Jedi. Yoda may be the Jedi that people put on a pedestal, but even he suffered from fear.