If you spend time watching /r/place you see that pictures mostly form in a natural, progressive way. This is the only place you see hundreds of pixels being changed uniformly all at once. Even bots would be making more gradual changes than this. It's clearly someone who has a brush tool for censoring.
player2
joined 1 year ago
The admins are blatantly censoring the drawing, putting checkerboard squares or circles of random color over that part. Here are some screenshots I took only seconds apart.
lol yes there's a whole underground imgur social network full of users unaware that imgur was originally just an image hosting website for reddit. By default the images I uploaded were private but I decided to click the button to make them a public post just out of curiousity of what imgur's opinion on the matter might be. Turns out it's not interesting for them.