I had the same problem with a PDF schematic for a BTT Octopus 3d printer board (which is published on their Github repo). Unsearchable, weird characters behind

I had the same problem with a PDF schematic for a BTT Octopus 3d printer board (which is published on their Github repo). Unsearchable, weird characters behind the curtain, and etc. But I don't blame deliberate obfuscation (or any other deliberate attempt to hide information) at all. Instead, I simply blame incompetence. (There's a ton of shitty PDFs in the world; this is just an example that I've encountered recently.)