https://en.wikipedia.org/wiki/Private_Use_Areas
I came across a Python library that passed the ASCII range into one of these non printable character ranges and then into a database. If someone was doing that manually with a hex table, how is that detected and mitigated?
Globally we’ve agreed that the ASCII code for a space is 32, 65 for the letter A.
Unicode characters are also globally defined, so when someone uses an agreed upon code, everyone sees the same thing, like this grimace smiley 😁
A private area is a place that we’ve all agreed is for “private use”. If a trademark owner wants to use their special character in their documentation, they can define one area to represent their character, but the only people who will see it in the same way, are people who installed their particular font.
Anyone without that font would see whatever the font on their own machine displayed.
Putting random stuff in such a place is no more than putting gobbledygook in a text and it might even be used as a way to fingerprint text.
I’m not sure what you want to “detect” or “mitigate”.