I find the implementation of Firefox containers extremely frustrating to use.

The Firefox containers require that I keep my current context in my mind when taking any action.

If I am on a container tab for for and I press "cmd-t" to get a new tab, I do not get another work container tab. Instead I get a non-container tab (or default container). Several times a day do I realize that I've been doing a specific kind of searching (google research) or general browsing in the wrong container.

This pollutes my container identity, history, and website preferences. My work search history is now full of non-work stuff. My search results are less relevant. My "goof around" container is now full of work results, and vise versa.

I prefer the Chrome model, where one whole window, and all it's tabs, are one "profile". This makes it much easier to use and think about.