Hate to be a black cloud, but as much as I love containers, my containers and their settings often disappeared. I can no longer remember exactly why. it may be if i disabled containers and then re-enabled them. (Containers may be a source of glitches so disabling is to help with troubleshooting.)

getpocket.com needs to be logged in via container 0. if you put getpocket to a personal container, and don't login to getpocket from container 0, then firefox's save to pocket feature does not work.

i cannot save bookmarks to automatically open in set containers (personal gmail to open in one container, work gmail to open in another container, etc.).

Otherwise, containers is something i miss and i have used workarounds to implement the same with MS Edge.