Accessing Modern Warfare

You do not understand the issue, you have to understand that there is modern warfare (not free) and modern warfare war zone (free)

For those who have a physical version, we can't access the original modern warfare campaign and other stuff from the main game that we purchased, we can only access modern warfare war zone, everytime we try to play the original modern warfare and not modern
warfare war zone it tell us that we have to purchase it. Even though we had paid for the physical version already.

You need to contact Activision, which owns and supports the Modern Warfare game, at support.activision.com as Xbox Support has no access to your profile for Modern Warfare; only they do.

Connection failed unable to access online services for modern warfare please help

This did not resolve the issue. I still do not have the option to access Modern Warfare. It only shows options to pre-order Modern Warfare 2, Play Warzone, or Purchase Vanguard. If I view it in the store it says I own the game.

Game pass to play modern warfare multiplayer? That is something new. I used to access it with no issues.