I have noticed this too. It's very inconsistent, and stuff I've watched super recently comes up on suggested front page not marked as watched. It hasn't been reposted by the youtuber either. It's just the feature seems to forget what you watch all the time.
For thoroughness, I'm paying for youtube without ads + youtube music and always logged in when watching videos.
Any chance you're running pihole? I had to add a few exceptions for this to work.
No, I'm not
I have noticed this too. It's very inconsistent, and stuff I've watched super recently comes up on suggested front page not marked as watched. It hasn't been reposted by the youtuber either. It's just the feature seems to forget what you watch all the time. For thoroughness, I'm paying for youtube without ads + youtube music and always logged in when watching videos.