Numbers error: not enough space in iCloud
This sort of weirdness sometimes comes about with versions and saved application state where the application doesn't want to let go of some data you added.

Do you have a Time Machine backup of the file in question? If not - be sure to copy out any data or log into the cloud version of numbers to be sure you have a cloud version you can live with.

Then clear the saved application state for Numbers by moving this file to your desktop or placing it in the trash can:

~/Library/Containers/com.apple.iWork.Numbers/Data/Library


If you don't have a good backup, I'd get one before deleting anything from your Saved State folders in ~/Library and if the Autosave Information and Saved Application State folders are empty you may need to delete the entire container.

If you're not sure about navigating to ~/Library which is hidden or restoring these files from a backup - Apple Support might be a good place to reach out to, but if you're familiar with moving things from the Library - I've seen clearing these help with oddball errors that you know aren't correct anymore.