My guess is that excessive current is being pulled from too few pads, causing them to heat up, and cause that severe discolouration. It’s definitely not being caused by prolonged heat; the CPU has just not had enough time, plus, the discolouration is too localized.
Here’s some CPU discolouration on an Intel CPU. Notice it around the edges of the CPU, along with the top right. This appears to be more-so caused by prolonged heat to the CPU, and not just individual contacts getting very hot, as is happening to Wendell’s 1950X.
Wonder how long those CPU’s will work in the long run, if this discolouration is already appearing a few months into the release of thread ripper.