> I play Fortnite with my kids casually. I looked up a howto a few weeks ago, and my recommendations are still 25% Fortnite related content, even though I only watched one video one time.

In general I've noticed that YouTube favors your "newest outliers" (let's call them) over stuff you've historically looked at. Probably the rationale (optimization metric?) is trying to capture you into content that might add to your total watch time on the platform.