Here's what we know for a fact...
- the animation above comes from the Tumblr of Max Collins
- Collins resume includes work for Studio Yotta and Cartoon Network
- Collins posted this animated snippet, and then quickly removed it
When you look at a comparison of the characters teased for Sonic Mania, you can see that Collins' animation does feature someone who possibly lines up with the silhouette. Marry that with the fact that Collins hasn't detailed why he removed the test animation, and you can see why the speculation is running wild.