I own Minecraft Java edition, and if I use the old launcher I can still play the game, but when I am in the new launcher just the demo version is available. I think that it might be because the new launcher signs in with an Xbox live account that is attached to my Microsoft account, and I can't sign in with just the Microsoft account. So the launcher is trying to connect with Xbox and sees that I don't have the game pass and doesn't know that I own Minecraft through my Microsoft account and doesn't let me play.