AmneziaWG is essentially WireGuard with certain fixes to make it significantly less traceable by modern DPI equipment. These fixes are numerous and regularly updated as part of an arms race with the government.

For most applications Wireguard is used for, like tunneling to your own machine under normal circumstances, there's no need for those, they add attack surface, incur severe maintenance burden and put political pressure on the project. And as Wireguard serves as an upstream for censorship-resistant protocols, they would be threatened as well.