highly unlikely for many of them. SharePoint, bitlocker, Active directory, hyper-v, rdp, DHCP and MSMQ are all software/technologies that have decades of history and long pre-dated LLMs. seriously, do people not realise it was entirely possible to write insecure or bad code before LLMs?

Sure, that's true.

It is also true that Copilot is currently in use developing Bitlocker and Sharepoint. So I wouldn't be confident saying it was one or the other.

Especially if they made heavy use of offshoring, which I would bet they did.