A: If downloaded from APKMirror, no. But never install “Facebook 1.8.4” from torrents or unknown blogs.
A: No. The Facebook API endpoints have been removed. facebook for android 1.8.4 apk download
A: Around version 150–200 (2017–2018) might partially work. Version 1.8.4 is purely historical. A: If downloaded from APKMirror, no