I have attempted to upload an egg sprite to my game twice, and both times it has been moderated. In the asset manager, it says “This asset has failed moderation review”. As far as I’m aware, the image does not have any explicit or rule-breaking content. It is just an egg.
I recommend uploading the egg graphic and the spots separately - not because that’ll help it pass moderation, but because it will allow you to recolor the spots by tinting, which means you have to upload fewer things. (Although white spots might be interpreted as something straight-up inappropriate )