I love the idea of this add-on. It is a browser-defining feature that is a big reason why I am a loyal Firefox user.

But, it pains me to write this--Multi-Account Containers is _extremely_ buggy. The add-on crashes constantly (closing all of your container tabs and deleting all your custom containers), sometimes containers are mysteriously duplicated hundreds or thousands of times, sometimes it forgets which sites are assigned to which containers (forcing you to reconfigure them). At one point I had to delete my Firefox account, losing a paid subscription to Mozilla VPN, because MAC had corrupted my sync settings. BTW there are >700 open issues reported on GitHub: https://github.com/mozilla/multi-account-containers/issues.

But--despite being a buggy mess, I still love this add-on for what it does when it works, and for what it could be one day. So I can't give it anything less than 3 stars.