Comment 10 for bug 1950073

@guiverc It might then be worth seeing if you can narrow this down in the sort of way seen in https://bugzilla.mozilla.org/show_bug.cgi?id=1739992 and update the upstream bug accordingly.

I don't know how the site recipe mechanism works; it's possible that there's something which is fetched from the network if possible but falls back to a local copy if that fails, in which case the fix might not be entirely robust until the next Firefox release.