In Andor episode 7, we had Cassian's flashback of the Clone Troopers during the empire, roughly 2-3 years AFTER Revenge of the Sith, where Anakin Skywalker met his demise as the hands of Obi-Wan Kenobi on Mustafar and turned into the suited Darth Vader. 
Why are Clone Troopers still around during this time of the Empire? Why aren't there stormtroopers? The answer is because it took time for the Clones to be thrown out, and for the Stormtroopers to take their place.
Palpatine wanted a grand army, he didn't care anymore for the costly use of Clone Troopers. He wanted a new face to the empire, and therefore Stormtroopers were the way to go, but with larger numbers.
Learn more about your ad choices. Visit megaphone.fm/adchoices