Welcome to the world we have created. I have a number of artist friends who get accused of posting generated art when it’s theirs. It’s just the new standard from now on.
Data provenance is going to be more important moving forward from here, especially if copyright rules lean away from allowing generative AI outputs to be copyrighted. Providing demonstratable proof you were the original author of a work--whether it be writing, artwork, movie editing or code--may become the standard rather than the exception