PSN users are reporting issues signing into their accounts after a new ToS was rolled out by Sony, however, there appears to be a rather simple fix for it.
If you are one of the users that appear to be affected by this new bug, it is related to a new privacy change that is being introduced by Sony. They have also announced a new trophy update that changes the way users will gain trophies and level up their profiles through points.
While the changes are being rolled out today, they apparently come with a change to the terms of service on PSN. These updated terms of service must be accepted before the user can sign-in into their PSN account and this is leading to some strange issues where they remain logged out.
According to this helpful thread on reddit, the simple fix for this issue is to just go to your profile and access your friend list. This will bring up the new terms of service which have to be accepted and you can finally sign-in into your PSN account.
If you are facing this issue then try applying the fix mentioned above. Make sure you have accepted the new terms of service in order to gain access back to your PSN account.