Quique Setien has made a public announcement that despite Barcelona announcing he and his staff were fired over a month ago, they only received official notification from the club yesterday, and that the club is trying to not pay them any kind of severance. Also Barcelona are saying they won't get severance because they will be given different jobs at Barcelona in the future.
So now they're getting hit with essentially a constructive dismissal lawsuit, which you'd imagine will be a home run given Barcelona's literally public announcement that he was fired.
It all boils down to them having no money. They can't pay off Vidal to make him leave, nor Suarez, nor Setien and they've asked messi for a pay cut.