I’ve had the exact same issue over the last several days; almost as soon as Avengers finished its first screenings, my YouTube recommendations and auto-play suggestions were filled with videos from channels I’ve never heard of talking about the film. The same happens weekly with Game of Thrones (I’m less concerned by that one being spoiled, but it’s the principle/behaviour that’s the issue).
“Look, I know the internet is dark and full of terrors if you’re not up to date on your favorite bits of pop culture. I should know better than to think I can completely avoid the zeitgeist around Avengers: Endgame and the latest season of Game of Thrones. But for years, I’ve done just fine staying …”