Definitely an AI fake.

A complete Rainbow... photo was taken at around 30k ft above the Earth. On the ground, we usually only see the arc half of the circle.
Credit Photo: Lloyd J Ferraro
There seems to be doubt about the authenticity of the pic:
https://www.reddit.com/r/Damnthatsinteresting/comments/11c6yii/complete_rainbow_taken_from_30000_ft_in_altitude/

More details/photos: http://bit.ly/3SvxXbw