I'm reporting that against Quay Hosted but I bet the same bug would happen with on-premises Quay Enterprise on or out of OpenShift. I just don't have a big instance, with hundreds of images, to reproduce that bug.

I have a public image that's the sampe app from a very popular blog post in Red Hat Developers
https://quay.io/repository/flozanorht/php-ubi

But if I search for its complete and exact name, that is "flozanorht/php-ubi", neither podman search not quay.io search page list it as part of the search results.

How to reproduce
run in the shell: podman search quay.io/flozanorht/php-ubi
open in a web browser: https://quay.io/search?q=flozanorht%2Fphp-ubi

Expect results:
flozanorht/php-ubi is among the first results

Actual results
flozanorht/php-ubi is nowhere in the search results.

The fact that I cannot trust search results and cannot find any info about how they are sorted and how the search term is matched makes the search feature useless and may trick customers into believing that content does not exist. It also hurts all customers, free and paid, that publish content in quay.io because users may not find they are there.