I ran a quick test this morning and this is what I found
iPhone 11 Running iOS 14.7.1
My Apple Music settings are:
Cellular Data - On
Cellular Streaming - High Efficiency
Lossless Audio - Off
Dolby Atmos - Automatic
Download over Cellular - Off
Download in Dolby Atmos - On
Atomatic Download - On
Animated Cover Art - Wi-Fi Only
I reset my Cellular data statistic then disabled Wi-Fi and listened to 5 songs over the course of 12 minutes. I listened to each song for 2-3 minutes before skipping to the next song. After I checked the cellular data usage and Apple Music used 104 MB of data. That’s just over 20 MB of data per song or just over 8.5 MB of data per minute. I’m not sure if that’s normal but it sounds pretty high to me.