the game is on demo and It can't connect to minecraft services

hi.

I bought minecraft java edition for my cousin and there is a problem which I cannot find a fix for it. when I logged in to his microsoft account everything was fine in the launcher except it says that he's not connected to the minecraft services and his game is on demo mode. I checked his email on the website and the game and they were the same. also this is not a internet connection problem because the news and patch notes load. I even logged in to his account on my own minecraft launcher and the problem was still there... I have a mojang account and everything is fine but he has microsoft account. I think it's a bug