Welcome to the community, @Richard.Parsons!
Wow, very cool! I think you have just publicly revealed for the very first time a brand new feature that Airtable is testing!
Airtable will often choose certain users to partake in tests of new features, so your friend must have been chosen as part of the test.
This is the very first time I’ve seen this new feature, but this looks awesome! And it is much needed, too! Very cool!
This feature has not yet been announced & is not yet available to the general public, but my guess is that you might be able to get in on the test by emailing email@example.com.
This new feature also looks like it will remove one of the big reasons that people turn to Stacker.