The question, firesticks, is where did you store the Numbers files?
On both the MacBook and the iPhone, there is both the ability to store the files Locally (in Local Storage) or on a Cloud Service (both have iCloud available, by default, but there are multiple options to take advantage of other Cloud Storage providers, such as Google Drive).
The Numbers apps, on both devices, will default to either Local Storage or iCloud, but can use other Cloud services.
If you use Numbers through iCloud (the Web interface), you'll only store within iCloud.
Additionally. iCloud Storage is tied to your Apple ID you used to access iCloud: Different IDs, different storage (even on Family plans, though you can have shared Folders).
If you wish, we can provide some pointers to find where you stored those files.
Please help us help you by providing us with some indication of how you have been accessing Numbers files: Numbers on iCloud? Numbers Apps on the Mac and iPhone?
Did you switch Apple IDs?
Anything else that may have changed, since the last time everything seemed to be working OK?