LLMs often use emdashes in a distinct incorrect way. It's not just the existence of any emdash, although considering you were in a very small minority of older users, it now warrants increased scrutiny, unfortunately for you.

if 99 poor effort/quality projects have a readme that reads in a particular style, then you expect the 100th project with a readme in the same style to also be of poor effort/quality

statistically, it only makes sense for your expectations to immediately be low when you encounter this writing style because there are just so much slop out there

the author is free to keep that writing style but they should be aware that this will—at least on the surface level—make their project look exactly like the metric ton of slop we see posted everyday everywhere