I have spent much time trying to solve this problem. KOreader is okay for looking at a document, but not for long reading sessions.

Unfortunately I have had to go proprietary and use readera premium, which works fine for epubs.

Try Librera if you haven't.

Yeah I tried that and I actually still have it installed. It's better for pdfs because of reflow but the ui is too much with all the buttons. Ty for the suggestion though.