linkp: Thanks for the input. I also use KeePassXC but the desktop version rather than the browser version, so that doesn’t interfere for me. The Eno extension is important for me so I added it back and will, for now, live with Brave’s poor handling of PDF inconvenience. I may switch back to Firefox. I agree with you that “this as an issue with Brave rather than the extensions” because I also have FireFox and Chrome installed, both with the Eno extension installed, yet they have no problem viewing PDFs in-browser.
BTW a good test PDF file is at https://www.learningcontainer.com/wp-content/uploads/2019/09/sample-pdf-with-images.pdf