As for the evidence that came later, Yoda believed that the Jedi had already lost by participating in the Clone Wars. He wanted to prevent
To summarise: Master Yoda could not warn the other Jedi about Order 66 because he did not know about it until it happened. He knew the Jedi would die, just not how or when the blade would drop.
Because, as Obi-Wan explains, the man he knew as Luke's father was dead to him, after being transformed into Darth Vader. Additionally, if Luke had known that Darth Vader was his father, he would have rushed into a confrontation too early, which would have undoubtedly resulted in him turning to the Dark Side.
However, most specifically, Yoda could have prevented Order 66 if he'd paid closer attention to his own Force visions. In the Star Wars short story anthology The Clone Wars: Stories of Light and Dark, Yoda has a vision of dark happenings surrounding the clone troopers.
Yoda didn't specifically know how this would go down, or to what degree Anakin would cause it to happen, but he was playing a much longer game by Revenge of the Sith, and that's at least, in part, explained by Yoda's Force connection with Qui-Gon's spirit.
Without Order 66, Palpatine would definitely lose. If Order 66 happened but not for some of the most powerful Jedi and the more battle-hardened and experienced Clones, Palpatine still loses even though many Jedi are killed.
Palpatine admits to Darth Vader that the Jedi he actually feared most was none other than Jocasta Nu.
As powerful as Darth Sidious may have been, it's easy to forget he actually seemed afraid of Master Yoda.
Why Qui-Gon Jinn Was Palpatine's Greatest Threat. Unlike Yoda and the Jedi High Council, Qui-Gon Jinn was only concerned about the will of the Force. Therefore, Palpatine needed Qui-Gonn out of the way because he was better connected to the Force than the other Jedi.
A new Star Wars canon novel confirms Yoda did recognize R2-D2 when the astromech droid arrived on Dagobah with Luke Skywalker. Star Wars confirms Yoda recognized R2-D2 on Dagobah in The Empire Strikes Back.
Luke Skywalker eventually had the lightsaber in his possession after Yoda's death in 4 ABY. Five years later, he offered the weapon to Grogu in a choice against obtaining beskar armor. However, Grogu chose the beskar armor over the lightsaber and went back to Din Djarin.
R2-D2 was in on the scheme to keep the secret away from Luke and Leia. He was devoted to the Skywalker family, and at the guidance of Obi-wan and Yoda, he would have maintained that secret in order to help protect the twins.
Jedi must always cooperate in battle or crisis. Jedi must not have wants; self-reliance must be shown. Jedi are forbidden from ruling others, although by the end of the Republic there was some debate over whether or not this was part of the actual Code. A Jedi Master may not have more than one Padawan.
Presumably Palpatine planned to have Anakin join him at that point and so told the clones not to kill him when he gave out Order 66.
Master Yoda failed Anakin Skywalker in Star Wars: Episode II — Attack of the Clones, and it resulted in the destruction of the Jedi Order. Master Yoda is one of the most revered characters in the Star Wars universe, and for good reason, but he ultimately failed in stopping the rise of the Sith.
Arguably, Qui-Gon is wiser in some ways, given that he knows how to preserve his consciousness in death. Yoda is wise, but sometimes flawed, given that some of his views align with the problematic thinking of the Jedi of this era.
Even after his brutal scorching in the fires of Mustafar, sand remained the only natural phenomenon that Vader feared. To him, sand was a reminder that he'd failed to save his mother or Padme from death.
That said, Vitiate, sometimes better known as the Sith Emperor, is often thought to have been stronger than Darth Sidious thanks to his mastery of the Dark Side of the force which granted him a ridiculously long life.
In non-canon material it is said that Palpatine had a number of concubines and never took a wife in fear that he would produce a legitimate heir. One of these non-canon concubines was Roganda Ismaren, a former Jedi who survived Order 66, and lived for a time at Palpatine's side.
Dooku, wanting more power, took up the mantle of Darth Tyranus. If he had stayed exiled on Serenno or stayed with the Order, Sidious would've been without an apprentice. Knowing the Dark Lord, he probably would have tried to find a place holder as Anakin was still too young to approach.
Amedda was one of the few beings in the galaxy who knew Palpatine's secrets, most notably his true identity as a Sith Lord. He was present on Naboo when assassins targeted Palpatine – another ruse intended to advance the Sith plot.
The Sith, an order of users of the dark side of the Force, was formed by fallen members of the Jedi Order after a war called the Hundred-Year Darkness. Eventually, after many wars, the Jedi defeated and seemingly destroyed the Sith in the final, decisive conflict. However, one Sith Lord survived: Darth Bane.