I'm not sure if I have any more info on this. No, I don't have Alex Sandro's contract in my hands, I do some digging by reading VS since I can understand a couple of words in Italian. I tend to read some pieces over there as they have a couple of people who report different stuff. Sometimes it makes it easier to understand what's truly going on in the club, sometimes it doesn't.
What we know for sure is that Paratici was kind of obsessed with plusvalenza and renewals because he had to lower the costs all the time, so that he could keep on buying. Agnelli had full trust in Paratici, so much so that he could do transfers on his own without anyone's consent. Remeber Cherubini's wiretaps where he complained that Paratici is crazy and without asking anyone can sign players for 25m just like that? Apparently that's the way he bought Kulusevski, everything happened super fast and suddenly we had a player costing over 40m on the books.
So, if you also put together what we know about contracts he offered to players, you begin to understand how big of a disaster he truly was. Le's look at some examples.
Ramsey: was signed on a free, got a nice package of bonuses when signed. Nothing extraordinary. Then, it turned out he had in his contract additional 'loyalty' bonuses for each year he stayed at Juve. That's why he was so difficult to offload, because the fight with him was for salary + loyalty bonus.
Szczęsny: His contract contains similar thing as in case of Ramsey's. This was mentioned at least one hundred times in here by
@Valerio.
Then, if you think that the clauses that Paratici put into players contracts were as simple as 30+ games, try to explain Szczesny's most recent automatic-contract-extension.
The player publicly criticized Allegri for the game style post-Sevilla and he gets a renewal triggered? Why is it triggered now, when his contract is expiring in 2024? Shouldn't he be collecting appearances next year to trigger it until 2025? It doesn't makes sense, especially considering the rumors that the's not happy and he'd like to leave and the club is looking to sell him as well (I think two gurus confirmed this on VS).
AS case is also interesting because the club extends him somewhere between February to April just to offload in June with severance payment? Who does that?
It makes even less sense when you take into consideration what Allegri's personal friend aka VS 'guru' (named "29-5-1985" over there) said... Apparently Allegri hates Alex Sandro because he's a stupid player and Max doesn't like players like that

He wanted him sold already post-Cardiff. Apparently AS was one of the reasons for frictions with Nedved who defended the Brazilian. Allegri wanted him sold.
Then, you might ask: why does he keep on playing AS still? Because the club decides, they loaned out Cambiaso and Pellegrini to lower the costs so Max is left with Alex Sandro as the only LB... The bottom line is: the club knows the details of the contracts, perhaps the renewal was unavoidable so they kept him?
I realize that these reconstructions might not be the most satisfying but those clearly show that in a lot of cases the club has contracts to respect and nothing can be done about it. You don't extend a player you want to offload and the coach doesn't want. So there must be something written down that gives the player an advantage, otherwise he'd be gone long ago.