PDF are not a native format that a web browser should handle ... and a browser should not expose any such addional attack surface through any pdf rendering engine, so i think it would be reasonable to move the existing PDF Viewer into an uninstallable addon.
People who want it can still install it (as a recommended addon), and those who prefer their system PDF Viewer dont have to think about it being a vulnerable/wasted part of the browser.
This will also (just like the removal of pocket hopefully) slim down the browser.
Thanks for reading.
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