From the screenshots it mostly looks like a DNS / hostname issue, not really an AKS problem.
Your ingress shows hosts like app22.20.96.66.53, but the Application Gateway public IP is 20.85.13.127. That will only work if there is an actual DNS record pointing that hostname to that IP. Since you mentioned that copying the URL gives a DNS error, it probably means the hostname cannot be resolved by the browser.
So the first thing to check is:
does that hostname actually exist in DNS and point to 20.85.13.127?
Another thing I noticed is that you currently have two public IPs:
one from Application Gateway and one from the Kubernetes load balancer (NGINX). If you are using Application Gateway Ingress Controller, the public entry point should normally be the Application Gateway, and your DNS should point to that IP.
For a quick test, you could also temporarily add the hostname to your local hosts file and map it to 20.85.13.127. If it starts working after that, then you know the issue is definitely DNS.
So I would first check the DNS record and which public IP your hostname points to.