You may be interested in my links on AI's writing style: https://dbohdan.com/ai-writing-style. I've just added your preprint and tropes.fyi. It has "hydrogen jukeboxes: on the crammed poetics of 'creative writing' LLMs" by nostalgebraist (https://www.tumblr.com/nostalgebraist/778041178124926976/hyd...), which features an example with "tapestry".

> Why is the instruction tuning pushing such a noticeable style shift?

Gwern Branwen has been covering this: https://gwern.net/doc/reinforcement-learning/preference-lear....