Going off search results, it seems to be a new coinage. I found mostly references to TFA, along with an (ironically obviously AI-written) guide with suggestions for getting LLMs to avoid the issue (just generic "traditional" advice for tuning their output, really). The guide was apparently published today, and I imagine that it's a deliberate response to TFA. But FWIW the term "semantic ablation" does seem to me like something that newer models could invent

At any rate, it seems to me like a reasonable label for what's described:

> Semantic ablation is the algorithmic erosion of high-entropy information. Technically, it is not a "bug" but a structural byproduct of greedy decoding and RLHF (reinforcement learning from human feedback).

> ...

> When an author uses AI for "polishing" a draft, they are not seeing improvement; they are witnessing semantic ablation.

The metaphor is very apt. Literal polishing is removal of outer layers. Compared to the near-synonym "erosion", "ablation" connotes a deliberate act (ordinarily I would say "conscious", but we are talking about LLMs here). Often, that which is removed is the nuance of near-synonyms (there is no pause to consider whether the author intended that nuance). I don't know if the "character" imparted by broader grammatical or structural choices can be called "semantic", but that also seems like a big part of what goes missing in the "LLM house style".

Bluntly: getting AI to "improve" writing, as a fully generic instruction, is naturally going to pull that writing towards how the AI writes by default. Because of course the AI's model of "writing quality" considers that style to be "the best"; that's why it uses it. (Even "consider" feels like anthropomorphizing too much; I feel like I'm hitting the limits of English expressiveness here.)