Username validation API shows suggested usernames without any change in username field

Describe your bug

When creating a new account in the codechef platform, username validation API validates and suggest different usernames that are not present in the codechef database. This API utilize too much resources if a user tries to check all the available usernames. I can able to see different usernames that are available in the without changing the username field by just clicking inside the username field and then click outside the username. If you repeat the same, it will provide the different set of usernames.

Steps to reproduce

  1. Go to the sign-up page of the codechef platform
  2. Enter the username
  3. Click outside of the username field.
  4. Click inside of the username field.
  5. Repeat step 3 and step 4, you will set the different set of usernames available

Test data

username: raj_kumar

Expected result:

It should show suggested usernames only if there is any change in the username field.

Actual Result:

It is showing all available usernames when there is no change in the username field.

Screenshot

Additional info

Browser - Firefox
Browser Version - 112.0
Operation System - Windows