"Invisible changes to pixels" means "a human can't tell the difference with a casual glance" - you can still embed a shit-ton of data in an image that doesn't look visually like it's been changed without careful inspection of the original and the new image.

If this data is added in certain patterns it will cause ML models trained against the image to draw incorrect conclusions. It's a technical hurdle that will slow a casual adversary, someone will post a model trained to remove this sometime soon and then we'll have a good old software arms race and waste a shit ton of greenhouse emissions adding and removing noise and training ever more advanced models to add and remove it.

You can already intentionally poison images so that image recognition draws incorrect conclusions fairly easily, this is the same idea but designed to cripple ML model training.