https://www.gamespot.com/articles/destiny-2-dev-admits-unacceptable-mistakes-of-lock/1100-6455572/

Following the launch of Destiny 2's Curse of Osiris expansion last week, players discovered that--as with Destiny 1--some activities became locked behind the DLC paywall. Players were understandably upset about this, and now Bungie has responded. In a blog post, Bungie started off by saying, "it's clear that we've made some mistakes with how we have handled content access."

The Prestige Nightfall saw its Power level cap requirement increased to a point that non-DLC owners cannot reach, rendering it inaccessible to them. The same is true for the Prestige version of the Leviathan Raid, which means it's not possible to earn the Achievement/Trophy for completing a Prestige Nightfall or Raid. Additionally, Trials of the Nine was affected by the recent DLC launch.