Interesting...low, normal, and high quality all can scale down in low bandwidth. Always high maintains 256kbps even if it has to buffer.
https://support.google.com/youtubemusic/answer/9076559?hl=en#zippy=%2Caudio-quality-on-wi-fiSelect or Change your Audio Quality - YouTube Music Help
YouTube Music Premium members can select the bitrate at which music is streamed and downloaded. If you haven’t selected a quality setting, it will automatically be set to the “Normal” bitrate fo
In YouTube Music, what’s the difference between High quality and Always High quality?