According to MOZ, the alternative text describes an image for robots and the visually impaired:
If you can close your eyes, ask someone to read the alternative text and imagine a version of the image that is reasonably accurate; It is on the right path.
What is Alt Text?
Therefore, your alternative text must be reasonably consistent and you must always describe the image itself. It is not necessary to include information such as "related image" in the alternative text. Instead, use a
h Element to introduce that section of the page to average users and users with visual disabilities alike.