Thanks JakeStoker for this article. We recently adopted Windows 365 as a quick way to scale up our distributed workforce.
What we have encounter is if a Azure AD user has two Cloud PCs with two different license types and the one of the licenses are removed, BOTH Cloud PCs are deprovisioned. After the grace period ends, the Cloud PC for the license that was removed is deleted (which is expected) and the license that stayed intact was then provisioned a brand new Cloud PC (not expected). You can see how this upset the user who's Cloud PC that they needed to keep was abruptly deleted. The Cloud PCs were in different provisioning policies and groups so it makes no sense why both of them would get deleted when only one license was removed.
I'm able to reproduce this scenario. It appears that you have to catch the Cloud PC you want to keep when it's in the grace period and remove the user from provisioning group then re-add the group membership for the license to re-apply. I've opened a Microsoft Support case and have yet to hear back on a reason why this is the case. Maybe you might want to test this out and add this to your post to help others that are using multiple Cloud PCs for one user and when it's time to deprovision just one of them.