The GDPR has beefed up the previous requirement to ensure that data that is superfluous to requirement is not collected.
Why would data about a person's gender need to be collected? I don't think data about sex is needed in most instances.
Is a person's sex needed on a passport or driving liscence?
Perhaps now is the time to challenge organisations who ask for data about gender?
In what circumstances should data about sex be collected? I can see why it is important for registering births and in medical settings. I can also see why organisations may want to monitor the sex pay gap and sex equality in the work place.