Many active players of Destiny 2 expressed concerns over the fact that some of the content, specifically the base-game activities in general, were not doable as they were locked behind the Curse of Osiris DLC. In particular, tons of players were left with nothing but pure frustration as they couldn't do any Nightfall activities and they couldn't enter the Prestige raid either. That basically meant that these players were unable to complete the achievements and trophy lists in the base game and they couldn't lay their hands on the spectacular Legend of Acrius shotgun either.
Following these events, Bungie issued an official apology on their website, stating that " their team overlooked the fact that these mistakes disabled Trophies and Achievements for Destiny 2". They also said that "this was an unacceptable lapse on their part and that they can understand the frustration it has created". Bungie explained further on that their basic goal was to have all the endgame content relevant at all times as the Guardians' powers rise with every new expansion. That would mean that the level cap for the Prestige raid would always increase as well and some max-level PVP content, the Iron Banner and the Trials would require the Curse of Osiris expansion in order to be functional. But, realizing that the end-result will not be what they expected, they had to release an update in order to fix these issues.
With the release of the newest update, the Prestige raid will, once again, have a level cap of 300 and the players will no longer need the Curse of Osiris DLC in order to access that content. At the same time, you would also be able to acquire all the trophies and achievements and you can also finish the Legend of Acrius questline. The Nightfall strikes, Trials and the Iron Banner can be accessed by all players as well (the only exception here is that they are still hosted on the DLC map). That being said, though, the Prestige Nightfall will still require the Curse of Osiris expansion and the same thing applies to all the achievements and trophies linked to it as well. On top of that, you will only be able to access them after completing the Prestige raid.
If you wish to see a full announcement of Bungie, make sure to check out the following link.