This thought often crosses my mind in particular when I consume media that is more 'psychological' in nature. Much of the time I can't shake the feeling that no matter how convincing the characters and their 'inner life' is presented, we're still ultimately seeing a projection of the writer themselves.
Sometimes I notice how certain characters seem richer than others, and usually these characters are obviously closer to the writer's own life. Perhaps this is why slice-of-life shows seem to do well (Atlanta, Better Things, Louie), because they're just the writers writing about themselves.
Or when I read a Dostoevski novel, I can't help but wonder how much of these character's inner lives are really just thinly-veiled versions of Dostoevski's (and, considering my love for his novels, probably my thoughts are 'compatible' with his).
What makes all this worse or more complicated though is that especially for television as a media, there are all sorts of pretty serious constraints. A show needs cliffhangers, ideally every episode, and at least every season, and unless you're on Netflix, you need mini-cliffhangers before every ad block. I imagine that's got to have some significant effect on the story.
I rather like this article by David Foster Wallace that sort-of goes into all of this: https://jsomers.net/DFW_TV.pdf (E Unibus Pluram: Television and U.S. Fiction).