Hi @Ravi Sankar
Application gateway does not support regex; Application gateway only supports * at the end of the path.
https://github.com/Azure/application-gateway-kubernetes-ingress/issues/1416#issuecomment-1185788051
https://github.com/Azure/application-gateway-kubernetes-ingress/issues/1028#issuecomment-736209506
Here is the list of supported annotations : https://azure.github.io/application-gateway-kubernetes-ingress/annotations/
Hope it helps, and please "Accept as Answer" if it helped, so that it can help others in the community looking for help on similar topics.