Maintenance for the week of January 19:
• PC/Mac: No maintenance – January 19
• NA megaservers for patch maintenance – January 21, 4:00AM EST (9:00 UTC) - 10:00AM EST (15:00 UTC)
• EU megaservers for patch maintenance – January 21, 9:00 UTC (4:00AM EST) - 15:00 UTC (10:00AM EST)
It's questionable since it's an official feature on PS4 to allow other PS4 players to play your game, it's up to the game developers to setup disabled areas that prevent this like boss fights.
Shareplay isn't account sharing. The other player is not logging into your account using your details at another location. It's a more nuanced issue certainly. It's money or in game currency changing hands that's actually the problem.