Hi, after a few unsuccessful times trying to play Cookie Clicker on the website and having it not load (website 404’d), I decided to look up where the site is hosted ( France). I then set my VPN connection as Paris, France. Tried loading Cookie Clicker and *boom*, instant connection, was back to playing Cookie Clicker right away.
If you use a VPN, I would suggest connecting to France, it might work for you, too.
Something that could also work is clearing your cache: the specific CDN where you get served cookie clicker could be down, and clearing your cache (by holding F5 and clicking the refresh button in Firefox, for example) might get you a working version!!