It's about 100 BBY, the High Republic Era. Vanity Fair gets the showrunner talking:
Palpatine is born in 84 BBY, eventual apprentice to Darth Plagueis of undetermined age."What is not being attended to? What are we turning a blind eye to that could lead to the rise of somebody like Palpatine about a century later?"
"If the light side is proliferating everywhere, what's going on with the dark side? How is it manifesting itself? What is it doing to survive?"
"If you want to explore Star Wars from the perspective of the bad guys, the best time to do it is when the bad guys are wildly outnumbered."