I'm viewing it from Ireland, and half way down the page, I see a full-screen banner for Disney+ with a notable personality from each of their franchises Moana (Disney), Mr Incredible (Pixar), Thor (Marvel), Jyn Erso (Rogue One/Star Wars) and Jeff Goldblum (National Geographic). I suppose that's what you're seeing?

Yeah same here, almost the entire landing page that I can see on my monitor is immediately just Disney+ advertising.

Nothing at all to hint I'm on nationalgeographic.com

Yes, that's it. Mr Incredible and Buzz Lightyear look very similar I guess.