>Then one day I went to the YouTube main page, and I saw that Google somehow got to know that I played Minecraft again after a decade

Did you play minecraft on the same network? If so, I'm not sure why the results are surprising or why it would negate all your efforts. If someone else played minecraft on your network you would also see a minecraft video on your main page I would imagine.

That's worse. My family or housemates can infer what activity I've been up to online by watching their YouTube recommendations?