Perhaps a watermark should be embedded in a subtle way across the whole image. What is the word? "Steganography" is designed to solve a different problem and I don't think it survives recompression etc. Is there a way to create weakly secure watermarks that are invisible to naked eye, spread across the whole image, resistant to scaling and lossless compression (to a point)?

Invisible, robust watermarks had a lot of attention in research from the late 90s to the early 10s, and apparently some resurgence with the availability of cheap GPU power.

Naturally there's a python library [1] with some algorithms that are resistant to lossy compression, cropping, brightness changes, etc. Scaling seems to be a weakness though.

1: https://pypi.org/project/invisible-watermark/

It's ironic, seeing people who build models trained on other people's work (which is in no way credited) to be worried about origin and credit.