It makes the preceding * less "greedy". I don't think it has any effect on the set of strings matched by this regexp, though, which is a simple string suffix check.
I agree, but the dot should be escaped because it matches any character, so "@domain\.com$" should just works for.
Or use [.] so it's super clear on the a-human-is-reading-it parse.
I don't think that's clearer because for [.] I need to remember that . does not need to be escaped in character classes whereas \. is quite clearly an escaped literal character without any advanced regexp knowledge.
I dunno, but I've seen a bug like this in prod while consulting.
Non-greedy match (match what's necessary nothing more.)
The default is greedy... match match match nom nom nom!