Windu eventually gets the better of Palpatine before deflecting his Force Lightning back against him, which appears to twist and melt Palpatine's face as his body begins to smoke, turning him into the grotesque embodiment of the Sith that acts as the final antagonist for both Star Wars: Episode VI - Return of the Jedi ...
In Revenge of the Sith, we see Darth Sidious seemingly deformed by his own deflected Force lighting. Right off the bat, this is by far the most popular and likely explanation for his appearance.
In the novelization of The Rise of Skywalker, Kylo Ren deduced that Palpatine's dark side spirit and power were too strong for the clone body to handle, causing major deterioration, which is known to happen to many dark side users – the stronger they get, the more damage to their physical bodies.
After quickly dispatching three Jedi Masters, in ROTS, Palpatine is left facing Mace Windu alone in a duel. Windu disarms Sidious, and the Sith Lord resorts to using Force-lightning agains this foe. The lightning is redirected back to its user by Windu's blade, and a lot of it ends up on Palps' face.
Why did Palpatine's skin turn white and wrinkly in his battle with Mace Windu? His own lightning bouncing off of Windu's lightsaber and reflecting back at him, burning his skin.
He understood he lost the ethereal battle before their physical fight even began. Thus, Palpatine never viewed Yoda as a major concern, even though the Jedi Master fought him to a de facto draw during the events of Revenge of the Sith.
As the Death Star had been destroyed, and the Battle of Yavin had finally taken place, the years then moved into ABY (After the Battle of Yavin). It's said that Star Wars: Return of the Jedi takes place during 4 ABY, meaning Palpatine was 88 when he met his original end.
Palpatine carried the lightsaber for a great deal of his life afterward, though he only rarely wielded it in combat, as his position as Emperor made battles with other Force-users few and far between, and he preferred to rely on his raw ability with the Force in any case.
Palpatine used his powers to hide his true nature from the Jedi, utilizing Force Concealment to completely hide his presence in the Force while clouding the Force for the Jedi. The Clone Wars also kept the Jedi busy and weakened, preventing them from realizing his true identity.
The fact that clones could defy the orders that are literally written into their brains caused a crisis of faith in the Empire. Since they couldn't command 100% control over the clones that they managed to ruin, regular conscripted soldiers offered an easier solution. Many of the issues were due to gradual mutations.
Summary. Some dark siders can conceal their appearance with the Force, hiding physical signs of corruption like yellow eyes and aged features. Palpatine's yellow Sith eyes may have been hidden through a dark side illusion, potentially masking his true form from the Jedi.
If the Sith made clones they would also not use Force Wielders because they believe in power residing in the hands of a very small number of 'superior beings' and the clones wouldn't qualify. They would know that an army of millions of Sith would inevitably turn on each other and make a useless fighting force.
Palpatine, motivated by pride and a desire to see his homeworld become a part of the greater galaxy, sought to quietly undermine his father's political agenda during the 65 BBY election season. More importantly, however, it was the rift with his father that indirectly led to his future as a Sith.
Palpatine understood the history of the galaxy as a constant war between the dark side and the light, embodied by the Sith and the Jedi. He sought to bring about the ultimate triumph of the Sith, extinguishing all trace of the light.
Well, first I will go over why he spared them. After Order 66, there were still a number of surviving Jedi. And while Palpatine knew that Vader was perfectly able to kill any remaining Jedi, there were too many for one man to kill alone. So, instead of killing all the Jedi he found, some were captured and tortured.
Legend had it that Yoda—a Jedi who became Grand Master—was trained by N'Kata Del Gormo. A Force-sensitive Hysalrian, N'Kata Del Gormo was trained in the ways of the Force and achieved the rank of Master within the Jedi Order.
Rumor had it that his mother was Palpatine's Umbaran aide Sly Moore, who had impregnated herself using DNA from an undisclosed source. Regardless of the veracity of that report, Triclops was regarded as the true son of Palpatine, both by himself and the few high-ranking officials who were aware of his existence.
As the ultimate villain of every Star Wars trilogy, Palpatine has hundreds of atrocities to his name. His plots and machinations toppled the Republic, ended the Jedi, and threatened to drown the stars in fire and blood unless the entire galaxy submitted to an eternal Sith Empire.
Yoda struck the Podium too hard to control his landing, and he rolled off the main portion to the edge where he desperately attempted to climb back up. His hold on the smooth edge failing, Yoda lost his grip and fell several stories to the floor. Yoda chose to retreat as Sidious cackled in triumph above him.
