A Microsoft file hosting and synchronization service.
It's not about YOUR OneDrive account being full, it's about your educational organization account being full.
This has to do with a change that Microsoft implemented end of 2024 for educational users. This change was explained here: https://www.microsoft.com/education/products/microsoft-365-storage-options
And I quote:
"Microsoft is making changes to our storage offerings across our Microsoft 365 for Education suite. Starting with their next contract renewal, but not before December 2024*, tenants at all institutions will receive 100 TB of free shared storage across OneDrive, SharePoint, and Exchange, with an additional 50 GB or 100 GB of shared storage per paid user for A3 and A5 subscriptions, respectively (not including student usage benefits)."
The key word here is "pool" storage. Therefore, this issue affects the entire account of the educational organization. You should contact your organization's IT department and let them know. They should visit admin.microsoft.com and follow this path: Microsoft 365 admin center > Reports > Storage to check the health of your organization's storage. If it's running low, they'll need to do a cleanup or contact Microsoft to upgrade the storage.