Remember back when Rust added new skin tones and other secondary attributes that players didn’t get to choose? Because the game just implemented another big variation between players: gender. Female models are in the game, and as with other character attributes, you don’t actually get to choose whether or not you want to play a female character. Your gender is determined based upon your Steam ID.
The update says outright that if you feel like you’re stuck in a gender you don’t want, there are lots of people who already experience that; it’s just that this is now determined by Steam ID rather than birth.
Other changes with this patch include armor and medical fixes, improvements to lighting and grass, and resource gathering. You can check out the full list of patch changes as well as some of the reasoning behind changes on the official site.