When renaming a file, the name is updated right away, the file is no more selected but underlined. Then, after around 2/3 of a second, Dolphin sort it and focus it even if focus was in the meantime changed to another item.
I personally think the current behavior with renaming file is useful when using the keyboard for renaming several items in a row, but Dolphin shouldn’t change focus if focus is changed manually (i.e. if any item is focused) before the end of the delay.
*** This bug has been marked as a duplicate of bug 388555 ***