Why end-3 /v2/<name>/manifests/<reference> counted as a pull?

My app using registry API to get image manifest (end-3 /v2//manifests/) only, there is no blob request.
I thought manifest pulling is not image pulling (download). Is this intended behavior? If it is, I think 100reqs/6hours is too small.
I have some images that I need to check to see if they are outdated. Is there an alternative way that compares the layer digest, but does not count the pull?
It’s like limiting Google searches to 100 searches every 6 hours.

That’s the quota for anonymous access per public ip.

If you need a different rate, then you’ll have to login using docker login.
The free personal subscription raises the rate to 200 reqs per 6 hrs.

If you need more, you should consider the pro subscription (see: https://www.docker.com/pricing/)