Maybe deleting the "ctrl + comma" shortcut will resolve this problem:about:addon(Settings, Add-ons and themes) > Extensions > Gear Icon at right-top(Tools for all add-ons)> Manage Extension Shortcuts > Firefox Multi-Account Containers > Ctrl+Comma > ...
The simplest firefox multi-row tabs solution:https://github.com/diyism/firefox-multi-row-tabs-userchrome-cssMozilla should implement multple-row tabs into firefox indeed!
