Youtube's recommendations may go beyond what you watch on the site?

Earlier today, I was reading some fanfiction for the Hunger Games on fanfiction.net, but I haven't watched a video related to the Hunger Games on YouTube or anywhere else in months, I believe.

Now, I log into YouTube and there's a clip for Hunger Games in my recommended.

I have a connection between the sites because I use the same email address for both of them, but I didn't even log into fanfiction.net today.

I know that what I do is being tracked by someone, but I thought until today they mostly used the info of your activity for advertisements, not to tailor your recommended.

If this is their way of being thoughtful, I don't appreciate it that much, lol.