https://www.gamespot.com/articles/forsaken-will-soon-include-destiny-2s-expansion-pa/1100-6462489/

Bungie has announced that, starting October 16, the Destiny 2 Expansion Pass will be included in the Forsaken expansion for free. The developer hopes this convinces more players to take the plunge and try Forsaken, as you need to complete Destiny 2's first two expansions--Curse of Osiris and Warmind--first.

Currently, the only way to get everything you need to play Destiny 2's newest expansion is by buying the Forsaken: Complete Collection, which includes Destiny 2, Curse of Osiris, Warmind, and Forsaken for $100. With the new deal, you'll get all of that for $60.