You'd need to get opt-in for sharing the data from LinkedIn with SlideShare though, because the contract between LinkedIn and the user does not extend to SlideS

You'd need to get opt-in for sharing the data from LinkedIn with SlideShare though, because the contract between LinkedIn and the user does not extend to SlideShare as a different entity. In my understanding: either they violated GDPR by sharing data with SlideShare, or they violate it by selling SlideShare to Scribd.