I don't know how or why this meme infects people; in my interview experience (MSFT, Google, Oracle, FB, Amazon, other smaller places) nobody ever batted an eyelid on me using C#. My advice would be to only use a language you know best, as long as it's appropriate for the role -- and most mainstream languages would be appropriate for generic FAANG SDE roles.
Using the language you know best will bring all sort of benefits -- you'll code faster, you'll be more confident, you might even find a place to show off a little. There is no good reason to give this advantage up.