Reddit went a step further and manually gigabanned the accounts so that whenever you try to visit an account banned for placing a tile - you get this page. (this is the ban crystalvulpine was talking about when he said he received the ChuckSpears treatment)

Example of an account chucked by the admins - they last posted yesterday proving it is a real account. As you can see, this was an active and real account that was not only banned, but deleted (the sub he posted in has now gone private, so this is an archive).

2nd example - proof (A)

Other people caught on, resulting in posts calling it out that reached the front page. Initially the admins tried to do damage control by setting a filter on /r/place to automatically remove any post that mentions the cheating or the Orange Cat that was overwritten. Another reddit admin responded (A) saying admins have been cheating to "keep the canvas safe for everyone," a laughably poor excuse considering they didn't interfere with people drawing peepeees, the 4Chan logo, or swastikas over the German flag.