A black box on a PDF is not redaction

Drawing a black rectangle, or highlighting in black, covers the words on the screen. The words are still in the file. Copy-paste can bring them back.

What Protect does instead

1. Find marks the text you choose, in yellow, so you can review it first.
2. Protect rebuilds a secured copy. The marked text is removed, so copy-paste cannot bring it back, and an AI tool cannot read it.
3. The black you see afterward is the space where that text was removed. It is not a cover sitting on top of the words.