I agree. There’s a similar problem in TROS with Dom Gleeson’s character. There’s a line he says in the background as Rey is grabbing the Jedi texts: “There were always whispers, of his hunger to cheat death.”
The idea that the galaxy “always” knew Palpatine was a Sith Lord is outright lunacy. Palpatine purposely did not want anybody to know that. I suppose it isn’t really a problem that the galaxy came to learn his true nature after ROTJ, thus why nobody questions his allegiance with the Sith fleet and Exegol in TROS, but the aforementioned line is problematic because it’s something nobody in the galaxy would have even considered while the Emperor was ruling.