Entropy here is referring to how random the user's password is, and thus how difficult it will be to guess it. For example, a four character password which can be comprised only of lowercase a-z has much lower entropy than a four character password which can have A-Z and a-z (and the case is significant).
I may be misunderstanding it. But they are switching the case, not turning it lowercase. So trying both AbCd and aBcD, because that's what you'd type if caps lock was on.
rezonant|2 years ago
Obligatory XKCD: https://xkcd.com/936/
Trrrrappp|1 year ago