Attempting to view unshared projects sends you to an error 404 page, like you probably know. So I wondered, what would happen if I replaced the "404" in the url with 403? Well, it's an entirely different error screen! Idk why this is on Scratch since you can't view it normally I modified Scratch Cat to look like the 403 cat.
https://scratch.mit.edu/403/ The cat isn't just a recolor of Scratch Cat, either. It appears to be a modified version of both 2.0 and 1.0 Scratch Cat mixed together. The entire head is 1.0, along with the fur on its torso, but the right foot is 2.0, and the left is much smaller.