Says who?
I could link you the part of the article that sums up what every journalist or guru that pushes for Pep has heard from their sources about that preliminary agreement. They've all got trusted sources and they're risking their credibility on that.
The problem is the article is in Italian so you'd have to be able to translate. I can translate it for you if you wish.
If you want a summary, the sources they have are from inside high-profile legal studios both in Italy and in the UK, and they all confirm a preliminary agreement was struck.
Preliminary. Which means it can result in nothing at all and Pep staying where he is.