A corrective update for Firefox has been released that fixes problem Ρ certificate, and re-enables disabled add-ons, skins, search engines, and language packs. The update is available for Windows, Linux and macOS (66.0.4 and 60.6.2 ESR) and Android (66.0.4).
However, some issues are still not fixed (for example, some users writethat the research is enabled but the add-ons are still unavailable), but the developers wanted to release the fix before Monday.
Source: linux.org.ru