Is there a way to side-step .PDF protection? [for non-nefarious purposes]

I have a couple of Brother products that come with .pdf manuals that I would like to highlight, add notes/comments to; but the .pdfs are protected. I.e., most of the manuals' contents are either obvious or irrelevant to my needs and I'd like to annotate to get to the bits that I'll need to refer to. I'm using macOS Preview. I'd considered just copying text and creating a fresh text document, but even text selection is blocked. I've tried looking at Sharing & Permission in Get Info for the .pdf manual. I am listed as having Read & Write permission, but this doesn't seem to be true. Staff and Everyone are Read Only. I can change them to Read & Write, but editing remains impossible. If I try to click the Padlock icon, I'm prompted for the protection pass again. The closest fix that I have, is to File → Export the .pdf as a .png. Then open the .png and File → Export to a .pdf, which I can annotate. It being a multi-step solution is fine, because it's not something that I'd have to often do, but the text quality is pretty poor. Is there a better way? https://preview.redd.it/ww32ujftj3ie1.png?width=1786&format=png&auto=webp&s=a2b59c33efd44bc637c734749e48f721130ed2a3