Unless you are the original artist, not citing the source of images might be flagged for plagiarism. Here is a post on why this is bad, and here is how easy it is to find allowed photos.

Not indicating that the image you post is not your original work could be seen as plagiarism, especially if you claim or imply to be the original artist.

Unless you clearly credit all media sources, you run the risk of being flagged and/or blacklisted by a growing number of anti-spam entities on Steemit. Citing Google as a source is not a legitimate use of an image. Even citing the original artist, does not necessarily grant you "fair use".

If you are actually the original author, please do reply, with supporting evidence, to let us know!

https://pixabay.com/es/coche-vehículo-1970-dodge-challenger-3149635/