Does anyone understand the PIP changes U-Turn

Ok, so spent all morning trying to research the PIP u turn changes and still non the wiser. By the look of it, and what people are saying on articles is it is still no good.

I read that Keir Starmer has been clever and he says it will not affect current people on pip. But, what I want to know is, when you come up for review when your pip comes to an end and you have to go through your review, do you go under the new rules.

So, basically is keir starmer lying.