Giving them the benefit of the doubt, it might just be to delay the payment.
Not if it's merely an "option". (They can still delay payment with an obligation...... We can agree 'gentle' repayment structure if we're agreeable too.)
They can just walk away having had him for two years and leave us with a player with even less re-sale value than he currently has.
We can loan again with a series of very easily hit targets that make the sale all but guaranteed. That way, Villareal get to delay the purchase until 23/24.
VR need to shit or get off the pot...... So does he if he wants to ensure a WC-squad place.