I wish someone at YouTube could explain, but the recommendation algo is nothing like what it used to be. Every refresh would bring a gem, now it's mostly the same videos, often from the same channel if I happened to watch a few in a row... Very odd.
I now find it over-calibrates to recommend based on recently watched videos, whether the same channel or the same style.
For example, I watched a video the other day, something like "Boris Johnson pronouncing the word _____". Next thing I know, my recommendations are flooded with similar videos that I don't really want to spend my time on.
This deters me from watching videos that come up that I'm mildly curious in watching, but don't really want to watch more of.