According to the rules the 6 should have been a 5 which would have put the weaker batsman on strike and of course another run would be needed from the last 2 balls.
It is quite amazing that no-one (either umpire, the third umpire (VAR), either captain, Sky Sports commentators and summarisers) were aware of the error.
Congratulations to England and also to New Zealand who have been magnificent in "defeat".