@nickcolley @benjojo It's illegal to ask for data that isn't specifically required for delivering the service. I guess that's how they justify data prediction - just that it means they don't have to ask for it.
Data protection allows to to request that any decisions made about you not be done via automated processes if you are not happy with the result. So I guess you could demand that discord have a human manually go through the data and decide your gender for you, and discord would be legally compelled to do so? If enough people demanded that it would certainly bog them down.