As of today, 28 Mar 2021, Facebook Container 2.1.2 is BROKEN for 78.9.0 ESR 64 bit. It worked in 78.8 ESR 32 bit, but locked me out after the upgrade. When I turn the extension off, Facebook reappears. Remove, restart, and reinstall doesn't help.
[edit] This version WORKS PROPERLY on 78.8.0 ESR 64 bit. I checked it on other versions running on my network, sync'd to the updated 78.9.0 ESR 64 bit.

عالی

Doesn't work

Had to remove this app. Could not get into some of my bank accounts.

Don't know what all the fuss is about, works fine with FF 86.0.1 on my Windows 10 machine. After listening to Snowden and reading The Intercept, this is a must-have extension. The future is private but certainly not they way FB or Google intend it to be! (and as a corollary, the intelligence community.) So be wise, be smart, and don't be used.

I've been using this extension for years. When the multiple containers option appeared not too long ago I assumed that it was a core feature of Firefox. I removed this extension temporarily while troubleshooting a performance related issue and was horrified to be dumped back into the vanilla Firefox tab experience. This extension needs more adoption! Not just with Firefox. Every browser should have this container based experience consideration by default!

Korreckt!