UPDATE 8/12/17: Bungie has said it will fix the "issue" where players are now unable to collect all of Destiny 2's trophies and achievements without buying the Curse of Osiris DLC.
"We are aware that there are some Destiny 2 trophies and achievements that have become unavailable to players who have not purchased Curse of Osiris," Bungie wrote in its latest weekly blog post, published last night.
"We are committed to fixing this issue, and are currently investigating a solution. Please stay tuned for more updates on this topic as progress is made."
It's not surprising to see Bungie react to this, as there are achievements and trophy requirements dictated by platform holders to ensure the game's full quota is available in the base experience.
But there's no word on Curse of Osiris locking out access to the game's prestigious Legend of Acrius exotic shotgun. The weapon was previously accessible without Curse of Osiris but now requires you to complete an activity pinned to the DLC's new level cap of 330 to obtain.
ORIGINAL STORY 7/12/17: Destiny 2 now requires you buy its Curse of Osiris DLC to unlock the game's eye-catching Legend of Acrius exotic shotgun.
You'll also need Curse of Osiris to unlock the base game's Platinum trophy (or on Xbox, net all of the achievements) if you haven't done so already.
Destiny has locked existing activities behind new DLC in the past - usually, whenever it has raised the game's light/power level cap and you need to be a higher strength to gain access.
But this is the first time I can think of Bungie has taken a weapon from the base game - in Acrius' case, a highly-sought exotic gun which you need to complete a particularly arduous questline to obtain - and then made it unobtainable unless you fork out for DLC.
Why do you now need Curse of Osiris? Well, the Acrius questline requires you finish the game's raid and then complete a particularly brutal Prestige Nightfall-esque version of the Arms Dealers strike.
There are further challenges beyond that, but its the strike which is the issue. Osiris raises the game's Prestige raid and Prestige Nightfall levels to 330. The game's base power cap was 300 - you need the DLC to progress higher.
While the Acrius' Arms Dealer quest step is still listed as 300 on the game's map screen, loading it up now shows you need to be 330 - just as with the regular Prestige Nightfall. Enemies are level 330 and you die very quickly if you are not.
The final portion of the Acrius questline, for the weapon's exotic ornament, is also locked behind the Osiris DLC. It requires a Prestige raid clear to complete (which is also now recommended power level 330).
Until it is completed, the questline sits in your Power Weapon slot and takes up a much-needed space.
And, if you don't have it already, you'll need to complete a Prestige raid or Nightfall to unlock the game's The Prestige trophy/achievement, necessary for Destiny 2's Platinum trophy.
We've asked publisher Activision for comment.