According to an email to Labs-l https://lists.wikimedia.org/pipermail/labs-l/2016-November/004789.html, the following has been removed from database replicas:
user_properties: language, skin, timecorrection, varient
This is a request for the risk analysis to be published on-wiki as to why this suppression was necessary, in the light of this never been shown to represent a risk before. There is a protected task T150679 which has been quoted as relevant. Presumably past versions of this same data can be mined from the public data dumps.