Not sure if the "trying to surprise Sony" part is quite right -- common sense would suggest that, like with the Xbox One, Microsoft is just running behind schedule and will launch pretty hot -- but I've talked to a few third-party developers who said they were frustrated by the lack of info on Scarlett, especially compared to Prospero.
Wouldn't surprise me if they decided to push their launch window to Spring 2021.
January VGChartz Articles:
http://www.vgchartz.com/article/441948/most-anticipated-game-of-2020/ (Article - Most Anticipated Game of 2020)
http://www.vgchartz.com/article/442015/ancestors-the-humankind-odyssey-xone/ (Ancestors: The Humankind Odyssey Review - 4/10)
http://www.vgchartz.com/article/442086/weakless-xone/ (Weakless Review - 5/10)