I mean, real deadlines do exist. The better heuristic is that, if a message seems to be deliberately trying to spur you into immediate action through fear of missing a deadline, it's probably some kind of trick. In this respect, the phishing message that was used here was brilliantly executed; it calmly, without using panic-inducing language, explains that action is required and that there's a deadline (that doesn't appear artificially short but in fact is coming up soon), in a way quite similar to what a legitimate action-required email would look like. Even a savvy user is likely to think "oh, I didn't realize the deadline was that soon, I must have just not paid attention to the earlier emails about it".

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nottorp 4 days ago | parent [-]

With credentials? Aren’t you always forced to refresh them right after a login?

As in right then, without being given a deadline…

	▲	ameliaquining 4 days ago \| parent [-]
		Yeah, this particular situation's a bit weird because it's asking the user to do something (rotate their 2FA secret) that in real life is not really a thing; I'm not sure what to think of it. But you could imagine something similar like "we want you to set up 2FA for the first time" or "we want you to supply additional personal information that the government has started making us collect", where the site might have to disable some kind of account functionality (though probably not a complete lockout) for users who don't do the thing in time.