A recent Twitter account has recently appeared online and it is named Prince of Persia. This could be the rumored upcoming mystery game coming later by Ubisoft.
Several Redditors found this new account recently and it seems to be made by Ubisoft. It has the @PrinceOfPersia username and has been set to private with no followers and not following any other account. It was created last month, which meant it was created just recently.
According to DualShockers who provided an image (check here), it shows that the account email has an Ubisoft domain. It is obstructed by asterisks to hide the whole email for security purposes, but it kind of shows it is from Ubisoft.
Since this is not officially verified by the company, there is no way to believe this right away. Take this rumor with a grain of salt. It could even be a very complex and elaborate ruse by someone out there trying to mess the gaming press.