Did you guys see the mercy Usyk showed against Joshua closing the 12th? He was was hurt against the ropes and could have whacked him a good 3 or 4 times to close the show, but he just watched him suffer..... Rest is history mates!!
Usyk said that he wanted to finish him but his corner said to back up a little. That is why he don't go all the way in the final seconds.
The fight was in the bag, no point going in for the kill and risk getting clipped no matter how small the chances of that happening are.