You don't have to be an expert; you should very rarely be using regexes so complex that you can't understand them.
https://devcraft.io/2021/05/04/exiftool-arbitrary-code-execu...
> "a\ > ""
> The second quote was not escaped because in the regex $tok =~ /(\\+)$/ the $ will match the end of a string, but also match before a newline at the end of a string, so the code thinks that the quote is being escaped when it’s escaping the newline.