What would they even say when posting the image, anyway?
"Here's a piece of art:"
"Here is a work of art:" they seem to be mine. "Here's a piece of art:"
You are right that point 2 can become point 3 in a certain situation, but if users are not banned, then, according to the forum rules, this is not plagiarism.
If this is a scam, then a flag should be set for this behavior. I read that some tribes had a custom at the beginning of our era. If a person was caught cheating, a flag was attached to him and taken through the streets so that everyone could see that this person was a deceiver.