"The game, which is in full development for the next-generation machine, is being deliberately withheld. Nintendo has not given the green light to all its partners to present their titles, especially those that would be exclusive to the Switch 2."
"Why this extreme secrecy?
Because it seems that any game exclusive to the Switch 2 requires special permission from Nintendo before it can be announced. This would be a strategy to control the hype and prevent leaks until the company decides to reveal more official technical information about its new console."Source: