https://wccftech.com/sonic-origins-datamine-reveals-new-sonic-frontiers-details/

Sonic Origins is now available worldwide, and some users started taking a look at the game's files, making some interesting discoveries in the process.

As reported by Arsenic on Twitter, the Sonic Origins files include references to content that will be found in the upcoming Sonic Frontiers, but has yet to be officially unveiled, such as Cyberspace levels, which are rumored to be the "Boost" style stages similar to those seen in Sonic Unleashed, Sonic Colors and Sonic Generations, and the return of Big the Cat and fishing. Apparently, these files are found in Sonic Origins because the collection's menus are built using the same engine, the Hedgehog 2 Engine, that is being used for Sonic Frontiers.