Apparently, it is a flurry of activity over on Sony’s official boards as this issue is being discussed, not to mention kicking up quite a fuss as well over on Reddit and XDA Developers’ forums. It looks as though this alleged pink spot is most most visible when one shoots an area that is predominantly white, gray, or brown. As for the intensity of the pink color, that varies from one user to another, so it is not exactly a uniform “experience” for those affected.
Of course, not everyone with an Xperia Z3 or Xperia Z3 Compact has experienced this issue even if they have tried their darndest best to reproduce it. Hopefully Sony will be able to do something about the situation, taking into consideration that the Xperia Z3 happens to be their flagship device.