I’m going to make a small comic series which will explain this from the POVs of the characters involved, but here’s a basic summary of his backstory

After hundreds of time-loops of Shadow Sonic going to 1991, something changed. Tails got the idea to clone himself alongside Sonic. Of course, due to the Cloning Machine’s faulty technology, the clone turned out having a different personality and the wrong colourations.

They let him perform alongside Origin as a secondary singer, and everything went smoothly. When Eggman got the night shift job at SFFD, Tails knew that he was just a night watchman and not a robber. He tried to tell Origin Sonic Eggman was just doing a job, but Origin couldn’t help but assume Eggman had ill intent, and Origin Tails couldn’t do anything about this.

And as you probably know, on Eggman’s sixth night, the bite of ‘91 happened. Origin Sonic and Origin Tails were brought to an isolated warehouse, where the lighting was awful and there wasn’t a lot of space to move around the place.

One night, Origin Tails snapped at Origin Sonic. He yelled at him for getting them locked inside this dull, grey building in the middle of nowhere, and whilst Origin Sonic attempted to resolve the situation, Origin Tails had had enough of him and found out a way to break himself out of the warehouse, leaving Origin Sonic behind. He was never seen again for 36 years…