It's not, Apple Music for Windows and Android both support Lossless. I'm not sure why Cider only supports 256 kbps. Maybe Apple locks it down so it's possible to stream it from first-party apps.
Currently, Apple's Musickit doesn't allow for Lossless streams to be accessed through their regular API. Fairplay encryption is to blame, and while it could be possible to get Lossless working, piracy concerns stop us from doing so. Keep an eye out on our X page, or head over to our Discord to get any updates on the situation.
