Reddit thumbnail

I found that only if the subreddit doesn't have an avatar, the thumbnail is correct.[1] Otherwise, the thumbnail would be the avatar of the subreddit instead of the post image.[2]

For example:
[1] https://www.reddit.com/r/stereograms/s/99CqBFB2U0
[2] https://www.reddit.com/r/nextfuckinglevel/s/eouN8qGiHO