For me that sort of thing actually dilutes the prestige. If I'm interviewing someone, and they have "I was an author on this amazing paper!" on their resume, then if I open the paper and find 1k+ authors on it, at that point it's complete noise to me. I have absolutely no signal on their relative contributions vs. those of anyone else in the author list. At that point it's not really a publication, for all intents and purposes. You may as well have just listed the project as a bullet point. Of course I'll dig deeper during the interview to get more details -- if you have something else in your resume that gets you the interview in the first place.

In short, I won't give your name on that notable paper equal weight with someone else's name in another notable paper that has, say, 3 or 4 authors.

That's how it works in most scientific fields. If you want more granularity, you check the order of the authors. Sometimes, they explaine in the paper who did what.

Contextually, yes. DeepSeek is just a hundred or so engineers. There's not much promotion to speak of. The promo culture of google seems well corroborated by many ex employees