Hi, I'm John!
Just to clarify, are you seeing this error in Outlook (email) or inside OneDrive Windows app?
After freeing space (or purchasing additional storage), it can take up to 24 to 48 hours for everything to fully update across your account. I’d recommend waiting that time and check again OneDrive after that.
If the update is still pending after 24 hours, you can try unlinking and relinking your OneDrive account, or resetting it. "Unlink and re-link OneDrive" https://support.microsoft.com/office/unlink-and-re-link-onedrive-3c4680bf-cc36-4204-9ca5-e7b24cdd23ea
If you're using Outlook New or Classic for Windows app, you can try to reset the Outlook app from Settings > Apps > Installed app, and sign out and sign in again.
If the issue still persists, please wait another 24 hours for everything to fully update across your account.
Click "Add comment" to let me know.
Regards,
John J.D.