How to allow list URLs correctly on a Cisco WSA Proxy?

Does allowing .kibbles.klausapp.com in a custom category on a cisco WSA proxy, also allows https://kibbles.klausapp.com/ ?

No, allowing ".kibbles.klausapp.com" in a custom category on a Cisco WSA proxy does not necessarily allow "https://kibbles.klausapp.com/".

When creating a custom category on a Cisco WSA proxy, you can specify the domain or subdomain you want to allow or block. However, the subdomain you specify is treated as a separate entity from the main domain. So allowing ".kibbles.klausapp.com" in the custom category will only allow subdomains of "kibbles.klausapp.com" that have "kibbles" as their subdomain, such as "subdomain1.kibbles.klausapp.com" or "subdomain2.kibbles.klausapp.com".

To allow access to "https://kibbles.klausapp.com/", you will need to add "kibbles.klausapp.com" as an exception in your Cisco WSA proxy's URL filtering policy or custom category.