How to get a VO2 Max

Hello, I'm new to Garmin UX and was hoping someone could clarify the VO2 max monitoring for me.

The Garmin instructions state that VO2 max can only be assessed by recording a 'GPS outdoor run' or 'ride bike with power meter.' However, my Fenix 7 generated a VO2 max score of 52, even though I never recorded a 'GPS outdoor run' or 'ride bike with power metre.' It did, however, recognize that I had walked, triggered by an IQ move with the last reading taken on the 15th NOvemebr. Since then, I've walked for at least 30 minutes, and these have been logged via IQ Move. However, my VO2 has not updated and is still showing November 15th. Can anyone explain the VO2 max feature and how and when it gets calculated?