More so than ever before, Destiny 2 is ready to start taking content out of the game and replace it with new content as part of Bungie's plan to make the game progress on a seasonal model. As old seasons transition into new seasons, content such as the Vex Offensive will go away. The removal of Vex Offensive and its status as a seasonal activity was well-communicated by Bungie, but the developer has provided a complete list of what is going away once Season of Dawn begins on December 10th.
Perhaps the most significant thing being removed from Destiny 2 is (as an effect of the seasonal ranks for season 8 ending) the ability to acquire Eriana's Vow. Once Season of Dawn begins, there will be no way to acquire the exotic hand cannon Eriana's Vow for players who don't already have it. The same goes for the exotic's catalyst quest, which is given players as soon as they pick up Eriana's Vow.
Eriana's Vow nor the quest are being removed, only the method by which players were able to acquire this season. Bungie did say that players who do not have the exotic hand cannon already will be able to acquire it in the future via different methods, but that will be a future release.
Bottom line is, it won't be available to find for the first time in Season of Dawn. So players should be sure to get it and add the quest to their inventory before the season ends. Quest progress for the catalyst will remain for those who have it already and will not be reset and continue working on completing it.
Like Eriana's Vow, anything on the season pass will be removed, so players need to collect anything they want on the season pass before Season 9 starts. They should make sure they have room in their inventory, as it is easy to miss a piece of armor, for example, that may not have been collected yet but is grayed out because a player's inventory is full.
Anything related to Vex Offensive is going away, including the 6-player matchmade activity itself, the Vex Invasions on the Moon, and the Vex Weapon Data Seeds from Ikora Rey. The seasonal artifact, The Gate Lord's Eye is also being replaced by The Lantern of Osiris in Season of Dawn, so the artifact, its mods, and the power bonus that players have earned from it over the course of the season will be removed and replaced with the Lantern of Osiris, which will need to be earned via the season pass and its tiers, mods, and bonuses unlocked.
Lastly, any season-specific Triumphs, seals, and titles—most notably the Undying title and seal—will be removed and unable to complete after this week. That title is tied into the Vex Offensive activity so with its removal, there would be no way to complete the title for new players. All this content will be removed when Season of Dawn begins on December 10, 2019.
Destiny 2: Shadowkeep is available now for PC, PS4, Stadia, and Xbox One.
Source: Bungie