An Artificial Green Rim.
The image captures a green segment on the top-left limb of the sun. Green rim is an optical phenomenon visible due to the refraction of sunlight through increasing density near horizon. The refraction of green light is stronger and thus a "green" sun can be visible higher than the "red" sun creating a green rim on the upper limb. Green rims do not last long and unlike greem flashes, they are not visible to unaided eyes.
In this image, however, such a refraction is caused by the heat and dust coming out from the turbine of the airliner engine when the sun is relatively higher in the sky, creating a green rim.
Gear: Nikon D5600, Sigma 150-600c
Exif: f/11, 1/500s, ISO 100, 600mm
Location: Kolkata, India
Date: 7th January 2021