As viewers will know, Tatiana and Berlin were divorced before the action began in season one.
The real reason behind this has not yet been revealed so far.
However, given how Berlin mentions to Rio (Miguel Herrán) he will not marry again from his past experiences, it seems like things did not end well between them.
Money Heist season 5: Are Sierra and Tatiana linked? (Image: NETFLIX)
This means Tatiana would have a reason to want to use the information she has on him against him.
Berlin is already dead by this point in the show but his brother and team would have to be the second-best choice.