Warning! This post contains SPOILERS for Tales of the Jedi
Thanks to the new Dooku warning the Jedi Council of the coming darkness and the growing corruption, the High Council kept close ties to the Republic during the prequel trilogy. However, they likely could have prevented the galactic civil war entirely.
Essentially, the complicity and hubris of the Jedi Council were the Order's biggest problems. Their decision to keep secrets and ignore signs made it very easy for Chancellor Palpatine to manipulate events in his favor. Likewise, the growing belief that the "Jedi claim peace but keep law and order for rich and powerful" as heard in Tales of the Jedi likely played a large part in many worlds choosing to the Separatist Alliance which would be led by Count Dooku. To that end, Dooku is seen in this new series beginning to carry the same sentiments while still a Jedi (making him ripe for corruption by Palpatine).
Could The Jedi Order Have Prevented The Clone Wars?
In Attack of the Clones, the creation of the Republic's clone army which had been secretly ordered 10 years prior was a massive red flag for the Council that darker forces were at work. Understanding that their ability to foresee the future with the Force had been diminished, they chose to keep that fact a secret from the Senate lest their enemies grow in response to their weakness. However, that choice was the culmination of the Order's longstanding complicity to the Republic's corruption (and their own pride).
The Jedi Council believed their Order was untouchable as servants of the light and keepers of the peace, ignoring the fact that they were only fulfilling the Republic's definition of it. Dooku came to realize these dark truths years before he was targeted by Palpatine who eventually convinced Dooku to betray his friend and fellow Jedi Master Sifo-Dyas and take over his secret cloning project on Kamino. Not only does Tales of the Jedi confirm Dooku's convictions alongside other canonical works such as the novel Dooku: Jedi Lost, it also shows how Dooku honestly tried to voice his concerns and reform the Jedi Order from within. If the Council had listened to him sooner and taken action, he might not have turned to the dark side, and the Clone Wars might never have happened at all.
Why The Jedi Order Had So Many Problems In The Prequel-Era
As Luke Skywalker says in The Last Jedi: “if you strip away the myth and look at their deeds, the legacy of the Jedi is failure. Hypocrisy, hubris." Unfortunately, Luke was all too correct about the Jedi Order and those who came before him in the prequel era. The Jedi Order and its leading High Council were far too connected to the corrupted Republic. Rather than keepers of the peace, they became soldiers of the most dominant government power in the galaxy, hence their hypocritical and ironic transformation into generals once the Clone Wars began. Dooku tried to warn them as seen in Tales of the Jedi, but the growing corruption pushed him into the arms of the dark side, mistakenly believing it was his only option to achieve true peace and order in the Star Wars galaxy.