As you know, each Office 365 services have its own domain, like .sharepoint.com, yammer.com or powerbi.com.
This fragmentation can cause some challenges for end-users and administrators.
Microsoft is now introducing a new unified domain for all Office 365 services: .cloud.microsoft
This unification under the .cloud.microsoft umbrella will simplify user experience by reducing sign-in prompts or redirect while help administrators reducing the allow-list.
At first, only new services will fall under this new domain. Existing services will slowly move under it over time due to a broader range of implications.
We can expect redirection from current services URLs under the .cloud.microsoft when the corresponding service is moving under it.
This does not impact other Microsoft cloud services like Azure; at least not for now.
More about the announcement here https://techcommunity.microsoft.com/t5/microsoft-365-blog/introducing-cloud-microsoft-a-unified-domain-for-microsoft-365/ba-p/3804961/