I’m on an iPad Pro 12.9, Gen 5 - MANY of us have the same issue and only with Firefox: You can move a tab, but it reverts to the previous position immediately. I have changed/adjusted/reset every setting that I can think of and nothing changes. You can move the tab - but it reverts to its original position automatically. This is a bug that Mozilla needs to fix - and, from what I have been reading has needed to fix for a lot longer than I thought… over the course of YEARS. With all of these complaints I would think that Mozilla would be working a little harder on this issue. It seems to me that it should not be that hard of a task within the programming - but that is just my retired IT brain thinking out loud.