We have the same problem in the O365 tenant of one of our customers. More than 20 users have Microsoft 365 Business Standard licenses assigned and they all had 5 TB OneDrive storage after we increased the default storage in SharePoint Admin Center one year ago. And it had worked not only for Enterprise licenses before, but for Business licenses as well.
But suddenly, since last week, the storage for more and more users (not all though) drops from 5 TB to 1 TB and cannot even be individually increased by Powershell cmdlet "Set-SPOSite -Identity https://[tenant]-my.sharepoint.com/personal/[user] -StorageQuota 5242880". After executing this command, the storage just remains at 1024 GB. If you try to increase it via the GUI in admin center, it says: "Maximum storage limit for this user is 1024 GB".
Even more strange is that some of the concerned users had way more storage in use before the drop, so that the usage bar in the Admin Center now says "426.1111 % of 1024 GB in use".
I created a support ticket with Microsoft and they called me back two days ago. It is a problem in their backend, Microsoft is trying to fix it until 14th March 2022. Let's hope it works then again!