Welcome to the Microsoft Q&A Platform.
Thank you for reaching out & I hope you are doing well.
From your question it looks like you are seeing if an exception can be put in to deploy a cluster in an unsupported version for testing (1.19).
Unfortunately, at this time we do not support deploying unsupported versions of Kubernetes in AKS. The below document covers our support policy.
Please "Accept the answer" if the information helped you. This will help us and others in the community as well. Feel free to reply with any other questions or concerns. Hope this helps!