They are pre-installed on all Android devices since 4 or 5 years ago or even longer than that. I noticed them on my S8+ after upgrading to Pie-9. They are hidden as system apps. I have never had Facebook or want it. You can't uninstall them so I deleted the data folder and removed any references to Facebook. Apps are permanently disabled for me. Facebook is trying to track everyone even if you don't like it. Why hide apps as system files?