When a custom domain is added for CF worker it changes the host URL
When I added a custom domain to my CF worker It changes host name in the browser URL. Url for my worker is https://wf-worker.support-c31.workers.dev/ However, I have added this custom domain wfweb.whoisfreaks.com. Attached is an image of worker code. PLease look into this issue.

WhoisFreaks
WhoisFreaks provides Live and Historical domain records through downloadable WHOIS Database and WHOIS APIs in REST JSON and XML format.