Action/Webhooks's 'URL to Notify' is not working as expected

Action/Webhooks's 'URL to Notify' is not working as expected

Hello,

The 'URL to Notify' field in the Webhooks doesn't accept wan't to accept whatever URL is passed to it.
For example consider we have the following URL: https://test.asdftre.com/api/ , it states that it is invalid, but there is no reason for it to be and thus I can't create my webhook, why?