Since it took a minute to figure out how to clean that up, maybe this helps other Firefox users: For me (vertical tabs) at least it was impossible to select mu

Since it took a minute to figure out how to clean that up, maybe this helps other Firefox users: For me (vertical tabs) at least it was impossible to select multiple entries in the history (ctrl + h) with the mouse. The workaround to remove the entries was to search for beatbar, tab into the list of entries, ctrl + a and right-click -> delete. History clean again.