Also....for me. At one point a janked up Firefox instlal on 8.1 created something like 100+ duplicates of some of my containers, specifically ones names TEst and Test2.
So each time i setup a new browser and sync then, i have to go through and manually delete all the duplicates.
They dont re-appear once deleted and changes still sync (ie: if i add a URL rule to always open in x container) but holy crap is it annoying.
ya know.....it never occured to me to really track down the json file. Even though i totally know firefox really loves making use of them. Even had a sanitize script at one point that would kill any session on my work computer nightly and scrub my history without logging me out of sync account at a previous job.
I dont setup a new machine all that often that I care too much. I figured it was a misconfigured cloud DB point, that at best I could get Mozilla to clean up and let me re-sync, but even then didnt bother to open a ticket.
There is a json file with the containers, I also had a similar problem (temporary containers extension “leaked” containers and they got synced) but after having found that file (I believe it was containers.json or something similar) and manually removing from that all the bad elements I managed to get those out from syncing it to new instances.
So each time i setup a new browser and sync then, i have to go through and manually delete all the duplicates.
They dont re-appear once deleted and changes still sync (ie: if i add a URL rule to always open in x container) but holy crap is it annoying.