This is probably because of the “overall rate limit”
Docker Hub also has an overall rate limit to protect the application and infrastructure. This limit applies to all requests to Hub properties including web pages, APIs, and image pulls. The limit is applied per-IP, and while the limit changes over time depending on load and other factors, it’s in the order of thousands of requests per minute. The overall rate limit applies to all users equally regardless of account level.
You can differentiate between these limits by looking at the error code. The “overall limit” returns a simple
429 Too Many Requestsresponse. The pull limit returns a longer error message that includes a link to this page.