How's windows OSSG team?

Everybody I know from there left (tens of people), either to different company or different org. Last I heard the culture didn't seem to be very good and priorities kept changing but everything is needed asap, but this could depend on where specifically you're looking (it's a big group)

Nightmare, career black hole

I was told it’s the team that works on encryption and stuff like windows hello .

It used to be a great team but the partner manager there left a year ago to Azure security and a lot of leads changed around that time. Work depends on the exact team you are in. Some own really old components. The team has many established folks which makes it hard for junior engineers to grow.