I grew up speaking 3 languages, and picked up a few more since then. To me it seems innately obvious that language is just a layer on top of the (much more complex) mental activity that goes on underneath all the time.

I do find myself thinking in one language or the other at times, but none is exclusive, often they get mixed together (the "next-token prediction" in my mind allows picking words in other languages that may more accurately describe an idea) and most frequently I do not have any internal dialogue at all.

I am pretty sure this is true for everybody, that the internal dialogue is not something natural but rather something people are so used to that we identify with it. Meditation and flow-state inducing activities (physical excercise, playing music, etc) make me think that this is the default for people, as these allow to access that lower layer of mental activity where internal dialogue disappears, even if briefly.