Yes, each Airtable account has a different API key. The used key should be of an Airtable user that has access to the base. If the user is removed, you need to update your API key in miniExtensions.
What permission level is needed?
The account that has its API key used in miniExtensions has to have at least a "creator" permission.
Would changing the email address of the Airtable account affect the connection between Airtable and miniExtensions?
No, as long as the API key is still valid.
I need to move an Airtable base to a different workspace. What do I need to do?
The API key used in miniExtensions is for a specific Airtable user. As long as that user has access to the base, the extensions will not be affected. Even if the base is moved to another workspace.