Garmin Forerunner 955 watch face data query

Hi, can anyone explain what the amber band is around the Forerunner 955 outer screen?
On the default digital and analogue screen, there is a line running from the 12 round to the 7. I’ve tried different data settings (hoping it’s a recovery indicator or something useful like that), but so far have found nothing to get the band to be displayed.

lol… watch it reaaaaaally carefully.