Earlier this past May, Sega broadcasted its first-ever Sonic the Hedgehog digital event known as Sonic Central. This gave news about the franchise's 30th anniversary, with updates to upcoming projects suchas as the Netflix series Sonic Prime and Sonic Colors Ultimate, a remaster of the original game on the Wii. At the very end of the showcase however was a teaser trailer for the next game in the series, though very little was shown off about what it would be about. Since that announcement, no new information about this new game has been given since.
Fans have been wildly speculating about what kind of game this will be, and much of the information fans have been searching for have been rumors and leaks. A lot of these point towards the 2022 Sonic title being named Sonic Rangers, which was used in a press release for the Sonic Central event. Sega had said that the title was incorrect and what was shared was an outdated version. A recent trademark from Sega might have indicated that this may actually be the case, giving the game a different title.
This trademark was discovered by @Renka_schedule on Twitter, who is an administrator for the Japanese Game schedule wiki. They announced that Sega had applied for a new trademark for a Sonic the Hedgehog title. These were for two titles known as Sonic Frontier and SONIC FRONTIERS, with a comment indicating that this may be the upcoming 2022 game.
This leads to a few possibilities about this trademark from Sega. It's possible that Sonic Rangers was the protoype name, and that this will be the official title going forward. This was the case with Sonic Forces, as it was once leaked as Sonic Wars, where the latter was the game's prototype title. The other possibility is that this is another project that is currently in the works, possibly a spin-off or side-game to the upcoming game. This however is all speculation for now.
The only other things that fans learned from the leaks is that it will supposedly be an open-world adventure, inspired by similar games like The Legend of Zelda: Breath of the Wild. A lot of these tied into the idea it would utilize the open-world for puzzles while the familiar Boost-gameplay would be reserved for separate "cyberspace" levels. Hopefully this trademark means that some possible footage could be shown off soon, and that it can give something fans to look forward to.
Sonic Frontiers is scheduled to be released in 2022 on PC, PS4, PS5, Switch, Xbox One, and Xbox Series X/S.