Is there a term for that phenomenon where someone gets so far into a topic that they become unaware of how much contextual knowledge they have about it?
Then they write some inscrutable technical docs, use unexplained acronyms, or tell a story about “he”, "she’ and/or “they” where you have no idea who they’re talking about.
I would say that someone is “in too deep” or something about “contextually saturated” or “contextually normalised”.