Managing personal Outlook.com account settings, security, and privacy
This may help:
My laptop updated to Windows 11 without my consent. It is a mess with way too many annoying "upgrades". For instance, to rename a photo, you have to right click then right click at the bottom to find rename...
So I cleaned up my email the other day and storage went down to below 5GB. The next day, storage was over 5G. Seems Microsoft sneakily added a "sync with Onedrive" feature. If you go to Settings>System, you will see "OneDrive" on the top right, just below is "back up files".
Click on OneDrive and uncheck the 3 boxes. Voila! Storage issue is gone. Somehow, it was storing my computer files (photos, documents, downloads) to a backup file in OneDrive. Be SURE ALL 3 BOXES ARE UNCHECKED before closing the window.
If you do want to back up your files, you will probably have to pay.