AMP spec:
https://amp.dev/documentation/guides-and-tutorials/learn/spe..."AMP HTML documents MUST..."
"The AMP runtime is loaded via the mandatory <script src="https://cdn.ampproject.org/v0.js"></script> tag in the AMP document <head>."
Do a whois on ampproject.org:
"Registrant Organization: Google LLC
Registrant State/Province: CA
Registrant Country: US
Admin Organization: Google LLC"
Note that jQuery, as mentioned in some GP comment has no such requirement. Google AMP is quite unique in this regard. This is NOT some general CDN type issue. Also...agreed, WTF is "open intent"?