"The Silicon Valley company and the F.T.C.'s consumer protection and enforcement staff have been in negotiations for months over a financial penalty" Honest question: What gets negotiated in this kind of settlement? What leverage does Facebook have in this situation to say, "no, that fine is too high"?
I'd assume it would look something like: "No, that fine is too high. We'll settle this in court(s) since we think we can do better." Now the FTC is facing a potentially big delay and a risk of no fine if the courts eventually hand Facebook a favorable decision.
The risk is much higher than that. There's a risk that a court rejects the entire justification for the fine greatly reducing both the ftc's ability to impose future fines and their power in general.