FF keeps automatically jumping to and highlighting the first instance of a string from an old ctrl-f find search. Moving to old tabs and opening new ones.
After using ctrl-f find to search for a string like "eg", FF starts automatically jumping to and highlighting the first instance of "eg" in tabs I move to, and new tabs I open.
(This is a really hard problem to google for, since all the obvious ways of describing it only involve really generic words like "find" and "tab". >:/ )
(I had this problem a long time ago.
I vaguely remember solving the problem back then by uninstalling some addon that extended the functionality of ctrl-f find.
However, this time the problem came back recently after I reset my profile.
So that can't be the problem, because this time I never installed any such addon.)