Sending, receiving, and organizing email in Outlook.com
Hello,
Please check whether your Microsoft Office 365 Family subscription is active in your Microsoft account.
https://account.microsoft.com/services
If you are not the family organizer, ask the organizer to check for any payment or billing issues with the Microsoft 365 Family subscription.
If the subscription is active but you still receive a storage-full error, ask the organizer to remove your account from the Microsoft 365 Family group and then resend the invitation for you to rejoin.
This may help the subscription benefits sync correctly across your Microsoft services and ensure that your storage is correctly reflected.
If you're the Organizer and you get the storage error,
go to the Services & Subscriptions page, select the Office 365 family subscription, and then turn off the recurring billing. Turn on recurring billing after some time. See if this resyncs your storage.
If you are still having issues, let me know.