Why is the feed algorithm so horrendously bad on Lemmy? I keep seeing the same posts I had previously seen/interacted with, even if I refresh the feed. Is it because this platform has not enough users?
Sounds like your sort is not according to your tastes. Try top n-hour. Remember to actually subscribe to communities relevant to your interest, then you can use that feed to see things that are more relevant for you.
Lemmy doesn't have an algorithm - it doesn't have any particular content to force feed you in an attempt to keep you engaged. You're not being shown what you might like, you have to select that yourself.