> Second, if you don't use monospace text, the width of the text you are redacting will reveal information about it.
If you do use monospace text, width reveals the exact redacted character count. If you don't use monospace text, it constrains the possible contents in a more complicated way, but it leaks information either way.
It leaks much less information when monospaced, although that information is easier to retrieve. Anyone can just visually inspect and see exactly how many monospaced characters were removed, but someone with the right tools and skills can narrow down the potential characters quite a bit if it's a short piece of non monospaced text.
If you do use monospace text, width reveals the exact redacted character count. If you don't use monospace text, it constrains the possible contents in a more complicated way, but it leaks information either way.