I was recently informed that Females who signed up after April 2016 are still on the 20% fee. Is this information correct. And if so doesn't that breach Ubers discrimination policy?
No this is incorrect. Uber don't even have a software to record your gender let alone adjust your commission DOWN based on something like that.
If it were true then yes. But then they would find a way to legitimise it by not applying it across the board, instead adding another factor like rating or acceptance rate etc.