This illustration was rejected because it contains elements protected by copyright (IP)

This illustration was rejected because it contains elements protected by copyright (IP).
But can you help me understand which part contains copyright? I've also attached the title and keywords.
I should point out that the image was taken from a site that authorizes commercial use and modifications, and that the map was drawn by me and not copied.
I thank anyone who will take the time to help me. Thank you all.

Title: Australia Map Silhouette on National Flag Background with Southern Cross
Keywords: Australia, Australian, map, silhouette, flag, national, country, Oceania, oceanic, continent, patriotism, patriotic, blue, red, white, symbol, emblem, identity, geography, nation, federation, independence, pride, culture, heritage, background, abstract, template, design, banner, poster, wallpaper, illustration, icon, shape, contour, outline, territory, travel, political, sovereignty, emblematic, southern, cross, outback, kangaroo