As far as I know all the development work on client projects was done by developers in India. I was too far removed from the details to know quite how they were employed and paid - I literally never had any interaction with them - but I suspect this is the main source of the LinkedIn employees.
As far as I know customers were aware apps were being built by human developers, the "80% by AI" was prominent on the website and the sign up process but it was never claimed the whole thing was automated.
It looks like Craig Saunders joined only a year ago, in June 2024, which is long after I left. Given how much AI has advanced over the last few years, and given his LinkedIn shows he previously held a senior AI role at Amazon, I wouldn't be remotely surprised if he and other employees built some impressive tech demos over the last year or two.
Regarding Natasha assigning developers to projects, I don't know to what extent it was really automated, I wasn't involved in that.