Similar to another bug report I’ve opened (Image thumbnail is not showing in some cases), the forum continues to show failures when reducing images a little wider, as in the example in this link:
There are several other posts with the same problem, scattered around the forum.
In the last bug report mentioned above, I asked why this is happening but got no response.
Then I see that NOTHING HAS BEEN RESOLVED.
This occurs on several browsers (I tested it on Chrome and Firefox, on my Windows 10).
However, if it’s any clue, I noticed that some of the posts with this problem on Windows appear normally if visited in a browser when on Android.
I think it should be in #forum-help:forum-bugs. It has been mentioned before that the DevForum tends to scrap old videos and images, but it appears it has done so with the thumbnails and not the actual image.
It may be possible the actual image is loading as the thumbnail instead of the actual thumbnail, or that there is a different thumbnail image for smaller screens (which is likely the case to conserve bandwidth on a cellular connection).
Images that do not have the image context actions (the white bar below the image) will not show this behavior, likely because there is no thumbnail because of the image’s size.