[^\.] # Any character that isn't a \ or .

Not exactly. The backslash is used as an escape character, not only in the regex itself, but in character classes too. Even though it's not necessary at all to escape a dot in a character class, Perl removes the backslash itself (Perl always does something when you use a backspace in an interpolated string, unlike some languages where "\q\n" is backslash, q, newline. In Perl, "\q\n" is q, newline.).

[^\.] # Any character that is not .
[^.] # Any character that is not .
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