Everything. Everything that does this thinks I'm Female. I am not Female.
They probably don't care for 100% accuracy. Most people's sex is trivial to identify. Age is much harder.
It is invasive for the following reasons, the technology is pushing to you instead of letting you choose how to interact with it. You can’t opt out or not consent to the tech. It poses a significant barrier to usability because what if there’s an offer for men chained to faces that the system thinks are male or vice versa? Now he’ll have to prove his masculinity to an algorithm or ask someone to intercede? That’s additional friction on top.
Pushing not pulling seems deeply unethical and counter productive.