I'm surprised that no one brought this up here yet, so I will do albeit a little late
Simon Aarons found out that Google Pixel's built-in cropping tool "Markup" does not properly remove cropped data from PNG images. What happens if you crop down to only 25% of the image? Well the other 75% of the image are not cropped, are not erased, the data remains in the .png file. Only the space needed for the 25% is overwritten in the file. If you shared this image, it's possible to recover some of this 75% data that was supposed to be deleted.
That's not all. It turned out, Microsoft's Windows cropping tool commits the exact same bug. God knows if this was intentional and how many sensitive images are out there now.
How did people not notice the image size not being reduced? At least Screenshot Captor shows the size in the info bar at the bottom
Original post:
https://twitter.com/.../163685747826375065613 minute video with explanation by Computerphile
