Determined sites could already easily do this. Just detect the patterns used. I agree it's a useless change though.
It shouldn't matter for the sign in with apple because sites are already expressly supporting that.
Email aliasing is hard because you want privacy from a herd of users, but then you're locked into that ecosystem versus a domain you control has no herd, but the upside is no lock-in.
> Determined sites could already easily do this
They already DO do it, I don't know how they're currently determining it
Not all aliases it generated look like this, some look like these:
In any case fact that some services banned alies is not the reason to make them completely useless instead of making them better.Apple is one of few companies that ia able to push for this with market share.