…so essentially WebP is fine for mobile devices and the vast majority of desktop web cases. I’m fine with WebP not being a suitable format for permanent storage of photography.

A close up section of the same zone in the images would make them visible. I could hardly see the artefacts in the first place as my attention was caught with the highly contrasted parts of the images.

No, I can see it on Android without zooming in. Not well for sure, but it is there towards the corners.