I think this kind of feature is on transak.com, a 3rd party provider that Metamask uses to buy and sell inside of their wallet.
It says it is only for first-timer customers, is this your first time doing the transaction with Transak inside Metamask?
I found this article from Transak:
Cooling-Off PeriodA distinctive feature of the new rules is the introduction of a 24-hour "cooling-off" period for new customers.
This measure is designed to allow first-time investors a window to reconsider their decision, thus ensuring they are not rushed into making potentially risky investments without adequate understanding and consideration