Have you by any chance been receiving this message on your PS4 for Destiny 2? "Your permission to access online multiplayer gameplay may have changed". Or maybe this one: "Your profile may have been sign in elsewhere." That's ok... you aren't alone. Apparently many others have been receiving this when trying to play online, and it has led to a horde of complaints from players.
Bungie is fully aware of the problem now. In one of their latest tweets, Bungie acknowledges that it is indeed a bug in the system, but they are hoping to resolve it soon.
We are investigating players on PlayStation 4 receiving errors indicating permissions to access online multiplayer may have changed.
This follows a host of other issues found on both the Xbox One and PS4. For such a huge community game, can we really be surprised? There are bound to be issues like this, and I hope gamers can at least be understanding and give Bungie a chance to iron it all out. More and more problems will in all probability be found for months to come, but I have faith in Bungie that they will get it right. The game is good enough to forgive these teething problems.
If you are encountering similar or other types of issues, don't feel afraid to contact Bungie support directly. They need to know about these problems; if it isn't reported then it won't be corrected. Be a champ, and get involved.