[Sysosmaster]

The thing to remember here is that the only way to hide (real world) data in an image is to reduce the amount of data in the picture... a blur or swirl leaves most if not all data just in the picture (although distorted) Any filter that removes data (such as pixelate or blacking out / whiting out) can be used to safely hide this data... Just remember to also strip out any unwanted meta data (Exif-data) and do not use layers but a 'flattened' version of the picture.

[kortex]

Pixelation is also attackable. Generate input (e.g. GAN) and apply pixelation until it converges. Probably won't be super accurate but enough to probably ID someone.

Black/delete (and flatten/rebroadcast) is the only way.

[freeone3000]

I'd worry about hallucinations when applying a GAN to a pixellated image. You'll get out a face, but who's to say that it's the correct face? Lots of people look similar.