Excellent addon. But it doesn't work since Firefox 89... Please update.

Note to creator: Here are my desired additional features (that the old MultiFox had):

Feature A.
Step 1. Click once on Multi-Container button, list of profiles shows up.
Step 2. Click on desired profile, new tab opens with current URL but with selected profile.

(In contrast, the Context Plus add-on requires that I (i) right-click on the tab; (ii) move mouse cursor down to "Move to Context" and wait for further drop-down window to appear; (iii) then "Ctrl+Click" desired profile.)

Feature B. The ability to rapidly open the same URL across multiple profiles. With MultiFox I could just click the MultiFox button, then click-click-click-click across all my different profiles and open up multiple tabs with the same URL, but each with a different selected profile.

(In contrast, the Context Plus add-on closes the earlier drop-down windows and immediately brings me to the new tab once I click on one profile.)

(The above was also posted at https://github.com/mozilla/multi-account-containers/issues/311.)