I agree it is laughable, it must be Covid that has turned a number of bluemooners to soft self entitled knobheads!
It's his last year, so Messi can buy himself out. As far as I'm aware, it's based on a formula derived from annual football earnings or something of that ilk. Failure to agree means that a court gets to set the fee, but that wouldn't be anywhere near £100M.
Messi, City & Barca will all be wise to this so I expect the fee to be £75M or less inc. any players. I suppose that the headline figure could be higher if a player going to them is over-valued so that Barca can save face.
‘. Undisclosed fee’ is my prediction..