If you're playing Call of Duty: Modern Warfare 4 on Nintendo Switch 2, beware: you're at a disadvantage in competitive Multiplayer due to crushing input lag that is much worse than the other platforms. Digital Foundry's analysis found that the input lag on Switch 2 can be two times longer than on PS5 at 60fps. In competitive Multiplayer, Switch 2 aims for 60fps and hits that target most of the time, although some things do cause the frame rate to drop. The debate about the advantage PC players have over console has dogged Call of Duty since the dawn of crossplay. Variable Refresh Rate support helps smooth out framerate drops on supported displays, although you'll have a harder time of it in terms of performance playing through portable mode. The responsiveness in portable mode ranged from 83ms at best to 125ms at worst, which DF called "actually deleterious to performance."
Outside of Multiplayer, the Campaign runs at 30fps, which was good enough for IGN's Simon Cardy when he played the Switch 2 version of Modern Warfare 4. The textures are nowhere near as detailed, with flat surfaces and faces smoothed over to give the impression of plasticine versions of the campaign's characters. It's by no means a looker, but considering the reduced horsepower Nintendo's latest console is working with, the gameplay itself was smooth, running at 30fps at 4K while docked.
The release on Nintendo Switch 2 has to do with Microsoft's $69 billion acquisition of Activision Blizzard, a 10-year commitment to bring Call of Duty to Nintendo following the merger.