During Gamestack live, in the opening speech after the countdown ends, the GM of Game Developer Experiences at Microsoft talks about how they use their technology across their 16 first party studios. Xbox currently only has 15, possibly hinting at them aquiring a new studio.

Its in here, right at the beginning after the countdown. Could be a counting mistake, but that was a prerecorded scripted speech so its unlikely. https://youtu.be/Noi5hj4N19U