We and our 838 partners use cookies

Exactly, it's about the cookie consent. I was a bit shocked when I saw that, and thought it's interesting, so submitted it.

I expected 10-50 "partners" but definitely not 800+.

I guess that is why most websites just list their "partners" and hope nobody will actually count them.

Afaik disagreeing should be as easy as agreeing. So I don't think it's a GDPR-compliant implementation. Also disagreeing should not be discouraged by visual methods (such as different colors) or making the button look as it's a disabled button (as it does in this example).