My opinion?
Not very bright people who don't have a lot going on in their lives have attributed something innocuous (the dog growling) to the painting and are now using it to explain evey single thing that happens to them when, previously, they'd have just said things like "ooh I'm feeling a bit chilly just recently."
Confirmation bias. People will see what they want to see and what fits their narrative. They have reified it by talking about it.