Basic functions work: in management mode, drag & drop one tab list item to another group; switch to group. The biggest problem is memory usage after long time usage of Firefox v 143 on a Mac Tahoe (not sure of other OS). The memory usage jumped from around 1GB to 7GB after upgrading MacOS to Tahoe version. In the background, must be keeping other OLD tabs in groups already closed but still open (not sure contents of pages already loaded). When I disabled this extension, suddenly more than 20 tabs popped out when total opened tab in all groups were about 7. Plus, Firefox now has implemented tab grouping feature same as Chrome: to collapse tabs into 1 group tab.