Comment by goyozi

The answer is quite simple, even if not satisfying: - recommendations take time to re-calculate - downvotes are not a global exclusion filter

There are a lot of approaches to recommendations, and I imagine the biggest players having a mix of them, so that _something_ sticks. Some of them might rely on data / features / models which are recalculated "once every X", so they don't react immediately to your input.

There's also patterns which are normal to some people but seem insane to others: "oh, I've liked this show so much I watched it 3 times!".