This is a very big misconception about AlphaFold. It's not generating a structure totally de novo from sequencing. Instead it's primarily finding relationships on the sequence level to other solved structures. If those structure/sequence relationships didn't exist somewhere, AF wouldn't work because it doesn't really have much information about protein folding from first principles. There are some small de novo elements, but nothing really groundbreaking. Where AF's true strength lies is in it's ability to detect relationships we have been unable to detect with any other method.