https://wccftech.com/destiny-2-patch-fix-access-content/

Bungie will be releasing a Destiny 2 patch later this week that will fix regular access to the Prestige Raid, Trials, Nightfall and time limited events.

As covered last week, the release of the Curse of Osiris DLC prevented players from accessing the prestige Raid, Nightfall, and Trials.  All of these activities were accessible prior to the expansion’s launch, but the expansion caused these activities to be moved to a separate DLC playlist and players who doesn’t own the Curse of the Osiris expansion simply can’t play the content that they paid for when purchasing Destiny 2.