Possible causes for connectivity issues:
Regenerating your Airtable API key.
An employee no longer has access to the base.
If the extensions were initially set up with (what now is) an invalid API key, then you need to replace it in the settings.
Regenerating the API key wouldn't only affect miniExtensions, it will break the connection between your Airtable account and any other 3rd party app (e.g. Zapier). All integrations will stop working.