Your keyword fetch-url-http-3A-2F-2F... is a typical example of a URL that was mistakenly encoded twice. Always decode before use:
import requests
When decoded, the URL becomes http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/ . This internal endpoint is accessible only from within the GCP environment (e.g., a Compute Engine VM, Cloud Run, or App Engine). Your keyword fetch-url-http-3A-2F-2F
Query straightened his brackets and prepared his request. He didn't need to look far; he knew exactly where the Oracle lived. He whispered the sacred string: a Compute Engine VM