Tried to use several different API endpoints as described in the link, but they all return 403 with a cloudflare "Just a moment..." html reply. Even tried copying an existing jwt token from a working logged-in browser but the same thing still happens.
I have no knowledge of this specific issue but 403 means unauthorized and the "Just a moment" response is usually because the server sends a JavaScript challenge to verify that you are a 'real' browser/user. It's an anti bot verification and you're not passing.