I remember interviewing there in 2009 and I stopped counting the number of languages I was told were being used on the SRO / backend side. I'm sure it wasn't, but it seemed like it was basically "everything" :-)
Most big companies use "everything" in some capacity, which is why "X uses Y" type statements are meaningless. The question is what's primary, what's supported, what's common in practice.
I assume there's still a big difference between big companies that have a monorepo and extremely centralized and vertical build infrastructure, and the ones that don't, especially if they're very siloed. From what I see from friends at Apple for instance, starting a project in an uncommon language is not a problem at all for most teams.
