Hello,
Welcome to Microsoft Q&A,
The issue is that the New images are published to the Azure Marketplace and show up in the Portal UI first, but CLI tooling (and even some regions) may not immediately support them until metadata syncs across all services.
You can use the PowerShell command below to find out if the image is available from the CLI
az vm image list \
--publisher Canonical \
--offer 0001-com-ubuntu-confidential-vm-noble \
--all \
--output table
For a broad search, remove the offer in the above command and see the available images from the publisher.
Please Upvote and accept the answer if it helps!!