Both the JP and the US soundtracks for Sonic CD use CD quality audio (hence the CD part of the name) (except for the past themes, which use the Genesis’s 16 bit sound chip in an attempt to sound ancient (and since these are hardcoded into the game, it was difficult for Sega of America to change them, hence the US soundtrack just uses the JP sound themes.))
I was able to click on the playlist OP provided, it’s all 8-bit renditions of the present themes (both JP and US (except Metallic Madness, which is just JP, probably a WIP)), hence why it’s labeled as 8-bit.
Both the JP and the US soundtracks for Sonic CD use CD quality audio (hence the CD part of the name) (except for the past themes, which use the Genesis’s 16 bit sound chip in an attempt to sound ancient (and since these are hardcoded into the game, it was difficult for Sega of America to change them, hence the US soundtrack just uses the JP sound themes.))
I was able to click on the playlist OP provided, it’s all 8-bit renditions of the present themes (both JP and US (except Metallic Madness, which is just JP, probably a WIP)), hence why it’s labeled as 8-bit.