Although Dooku still met with the Jedi Council on occasion, by that time he had secretly joined forces with Darth Sidious, eventually creating the Separatist movement and orchestrating the Clone Wars.

Source: https://screenrant.com/star-wars-jedi-council-members-what-happened/

By playing on the shortcomings of the Republic, Dooku was able to turn the galaxy against the Republic.

Source: https://screenrant.com/star-wars-count-dooku-name-origin/

During this time, Count Dooku tried to bring Mandalore into the separatist fold through a clandestine alliance with Death Watch.

Source: https://comicbook.com/starwars/news/mandalorian-star-wars-bo-katan-clone-wars-mandalore-history/

Either way, Dooku casually encouraging a youngling to walk a dark path clearly shows where his future allegiances will lie.

Source: https://screenrant.com/star-wars-dooku-origin-retcon-wookiee-apprentice/

However, Yaddle wasn't the only Jedi that Dooku killed.

Source: https://www.cbr.com/star-wars-count-dooku-murdered-fan-jedi-marvel/

In Attack Of The Clones, Anakin slaughters a large group of Tusken Raiders on his own before going on to go toe-to-toe with Count Dooku later in the same film.

Source: https://gamerant.com/star-wars-why-couldnt-anakin-beat-obi-wan-revenge-of-the-sith/

In league with the wicked Count Dooku, more and more planets slip.

Source: https://screenrant.com/star-wars-clone-wars-genndy-tartakovsky-changes/

Season 6 episode "The Lost One," it is revealed that Sifo-Dyas was killed by the Pyke crime syndicate on the orders of Count Dooku.

Source: https://www.cbr.com/george-lucas-typo-created-sifo-dyas-star-wars/

Still, one interesting theory is that Count Dooku believed he was the Chosen One foretold by the prophecy.

Source: https://screenrant.com/star-wars-theories-change-prequel-trilogy/

That changed when Ventress was betrayed by Count Dooku, forcing her to survive on her own.

Source: https://www.cbr.com/most-evil-star-wars-jedi/

The reason why Yaddle disappeared after Star Wars: The Phantom Menace has finally been revealed, and it turns out that Count Dooku is responsible.

Source: https://www.cbr.com/star-wars-yaddle-disappeared-count-dooku-theory/

This means that if fans want to play as Count Dooku or Rey, for example, they need to have played well or smartly enough in order to earn whatever requisite amount of battle points they cost.

Source: https://gamerant.com/star-wars-battlefront-heroes-villains-selection-battle-points/

When Dooku left the Order, he was still allowed to visit the Jedi Temple.

Source: https://screenrant.com/star-wars-count-dooku-name-origin/

When their plot failed, Dooku violently ended their partnership, but they soon became part of the Shadow Collective, led by the Sith pretenders Maul and Savage Oppress.

Source: https://screenrant.com/mandalorian-facts-star-wars-canon-legends/

With the demise of his apprentice, Darth Maul, Palpatine had Dooku prove himself as a Sith Lord by striking down his old friend, Jedi Master Yaddle.

Source: https://screenrant.com/star-wars-before-phantom-menace-timeline/