The case I am thinking about is absolutely hypothetical. The company XYZ asks an agency to create an advertising campaign. Outsourcing after outsourcing the work ends up on a gig site and it is done by a remote worker who uses images taken from Wikipedia or any other site with Creative Commons licence without telling it to the client.
What happens if a competitor or imitation brand XYz find out? Could XYz run a campaign using the same pictures? Could the competitor use those images to create an ironic version of the campaign?