All arguments in favor of the existence of other minds claim that other people have minds similar to my mind.
My mind is responsible for my behavior.
Other people have behavior similar to mine.
The best explanation for other people's behavior is that they have minds similar to mine.
If I have an internal monologue and other people do not have an internal monologue, then it turns out that my mind is not similar to the minds of other people. And so, in my case, my subjective experience, which includes an internal monologue, is responsible for my behavior, and in the case of other people, a completely different subjective experience that may not contain flashbacks and memories, for example, may be responsible for their behavior.
It turns out that I, by analogy with myself, will believe that other people have thoughts and memories, but in fact they may not have thoughts and memories.
Maybe I misunderstood something?