Error: GET requests to ServiceM8 CDN servers.

I'm getting errors when loading images in a browser or performing GET requests from Python's requests library to ServiceM8's CDN servers, for photos links in emails. The image still loads, but page continues 'loading' until there is a timeout error after 30secs. Below is an example error.

GET https://no-cookies-cdn.servicem8.com/view_branded_image?&s_vendor=84f4765e-31b7-4af3-b010-e4d0e5db3dcb&s_image=cb15d26f-8319-4e4e-8ece-e91da20faf8a&s_auth=be6c68c92470fcc0eeacb32e2d9598a1 net::ERR_HTTP2_PROTOCOL_ERROR 200