@MojangSupport I suddenly have no longer access to my java game. the launcher says java&bedrock, and I can only play demo

If you're seeing demo mode only, that likely means you're signing in with the wrong credentials. Check this faq out to see if it assists in this matter: msft.it/6015bWDOS for help. ^TK

I can login with these credentials just fine in bedrock though..

Did you migrate the account and are you signing into the Microsoft login instead of the Mojang login? ^Tk

the account was migrated long ago. I'm signing in using microsoft, just like in bedrock