Today's earlier sign in issues on PS4 should be fixed now. If you're still seeing the 403 error, restart and try to sign in again. Thanks for your reports and for your patience!
What about the people who have issues on Windows 10 and firefox auto loading channels over and over even if you don't click on them?!?! Playing a video in the background but wont display video just re loading channel page over and over and over. YOUR SERVICE IS HACKED/SHIT