As you know, you can setup a Site-to-Site VPN between your on-premises infrastructure and Azure.
This VPN connectivity involves the creation of a Local Network Gateway (LNG).
Until now, you add to configure a public IP for your LNG.
Well, good news you can now use a Fully Qualified Domain Name (FQDN) instead of the public IP. This is quite handy if you have to connect branch offices which may use a dynamic public IP.
To start using this new capability, logon to your Azure portal (https://portal.azure.com) and create a new LNG
Then you can switch to FQDN for the endpoint definition