For Opera developer version, for now the vpn is only available in private window. But in private window, the cookies and passwords are not saved after users leave.
This change has limited the scope of the use of vpn. The vpn should be available no matter Opera is in its regular window or private window.
I think it will be because of the vpn feature, users choose Opera other than others. Thus, the vpn should be available not only in the private window. It will be better to make vpn available in both of regular window and private window. In this way, Opera will attract more users.