I think this image should be set as cover, at least because in the source code it goes before the block with @itemprop="articleBody".
- 1 - all photos are nested in <div class = "photograph"> </ div>, so the image does not have its own class (the first paragraph of the rule 6.2.2)
2 - The user sees the image as part of the article, and not as a cover (the second paragraph of rule 6.2.2).
For clarity, I will give an example of an article with a cover - https://diletant.media/news/45244161/
In other cases, cover images are optional
- Declined by admin
- Type of issue
- IV page is missing essential content
- Apr 3, 2019