Except for the graphics team, as they were managed by someone else. They decided to go with C++, and they were pretty much always late because everyone was learning and building the tooling around C++.
https://kennykerr.ca/2019/01/25/the-state-of-cpp-on-windows/
As note, Midori did power part of Bing during its existence.
And Microsoft security is now advising to move new development into a mix of C#, Rust and constrained C++ (Core Guidelines).
Check DoD security assement of Multics versus UNIX regarding ease of security exploits, and how using PL/I prevented the large majority of them. On the mobile now, the document is accessible at the Multics history site.
Or any deployment of High Integrity Computing OSes for that matter.