We are talking about AirPods Max and AirPods Pro. This was reported by the T3 edition, citing a company representative. The fact is that both models of headphones use the AAC Bluetooth codec when connected to an iPhone, while Lossless files in Apple Music will be encoded using ALAC (Apple Lossless Audio Codec).
Perhaps in the future Apple will release an update and activate ALAC support in the headphones. This, incidentally, was hinted at by insider and blogger Jon Prosser from Front Page Tech. In the meantime, owners of AirPods Max and AirPods Pro will have to settle for Apple Music only with Spatial Audio mode with Dolby Atmos.