https://wccftech.com/advance-wars-12-re-boot-camp-delayed-until-spring-2022/

WayForward and Nintendo have announced that Advance Wars 1+2: Re-Boot Camp, the remake of the Game Boy Advance games, has been delayed until Spring 2022 from its original December 3, 2021 release date. The reason behind the delay is explained to be for more fine-tuning according to the announcement made by Nintendo of America's Twitter account:

Hello, troops! #AdvanceWars 1+2: Re-Boot Camp, which was set to launch on 12/3, will now release for #NintendoSwitch in spring 2022. The game just needs a little more time for fine tuning. You'll be battling with Andy & friends soon! Thanks for your patience. pic.twitter.com/dSi8VSsxTH