Work around found:
This behaviour is a problem with Evince, not Brave Browser.
Replace Evince with Okular, then right click on any pdf to bring up the properties dialog and on the “Open with” tab set Okular - Bob’s your auntie after that…
I have tried the latest nightly build as well as the stable release, if Brave is set to default web browser, clicking a hyperlink in a pdf document does nothing.
Setting either Firefox or Chrome as default, expected result - hyperlink opening in a new browser tab - occurs. This problem seems to have been around since at least 2018 in Brave+Ubuntu, and is a killer for me, I have set Chrome as my default, much and all as I otherwise prefer Brave.