I searched through Lemmy posts with that word. Half of them have people asking the exact same question, and based on the answers, I'm going to conclude that no one knows.
One guess that seems plausible is that it's an AI hallucinated word that's showing up a lot because they're using AI to generate the captions.
Ive asked the same question, the conclusion that I came to is it is a foreign word that doesnt mean anything in the context and is a give away to AI generated images.
I think it's this. I looked into it recently and there was a paper on AI and they noted "araffe" coming up as a caption when it was AI generated. They didn't have an explanation, said it was something to look into.