Sometimes I read expert-written blog posts or articles, targeted at a demographic the author is familiar in communicating with.
My brain will literally just turn off and I will go into a reading trance where I don't understand the text because my brain simply says 'yeah this is nonsense, don't get it.'
When I was working on my MFA thesis, I came to a realization that feels like it might overlap with what you're describing.
It's a little hard to put a bow on the idea (and why it isn't trite...) at this length, but basically: I felt a connection between the experience of trying to parse some intentionally difficult/impenetrable ~modernist texts, and the experience of trying to parse older texts where the phrasing is dated.
They're too unfamiliar to parse with fluent ease, and the experience of fluent reading is just fundamentally different. In one case, the text is like a Rubik's cube, and in the other it's hard to even realize it exists separately from your instantaneous understanding of it.
My brain will literally just turn off and I will go into a reading trance where I don't understand the text because my brain simply says 'yeah this is nonsense, don't get it.'
Very interesting phenomenon.