It has nothing to do with CSP. On "addons.mozilla.org" domain, add-ons are deactivated so Linkificator cannot do its job.
For github, this is the normal behavior because, by default, stuff in tags is not processed.
You can activate processing in these tags by editing 'Advanced settings' -> 'Configuration' -> 'Excluded Elements' and remove 'pre' from the list.
Please, can you use preferably support email to report problems rather than review.