VPS diskpace limit is configured in the service plan with different configurations (10GB / 20GB / 50GB / etc).
When a subscription is created, the actual limit assigned to the resulting VPS is the same - e.g. 10 GB - irrespective of the ST or SP configuration.
The service template contains additional resources, based on Diskpace resource class. For example, VPS backups space resource type was created incorrectly and added to the service template with 10 GB limit set.
Remove incorrect resources from the service template and leave only 1 resource based on Diskspace class.
Once the resources are removed, all subscriptions should be synchronized with their plans.
To fix a particular subscription without massive synchronization, it is possible to set the required limit for all resources based on Diskspace class.