Before I stopped using reddit, I was having this issue where it would literally show me the exact same post several times (like, not a crosspost, straight up the very same post) and it would get worse the further you scrolled. By page 5 or so, it’d be nothing but posts you’d already been shown. I just checked and it’s still doing it. I don’t know if this was just me or not, but it made it a lot easier to stop visiting.