Bungie recently announced that Forsaken Annual Pass would be given away for free to some players while Forsaken Complete Collection price is about to be slashed, causing a lot of distress and confusion across the Destiny 2 community.
Destiny 2 Forsaken Annual Pass includes three major pieces of content, released periodically under Black Armory, Season of the Drifter and Season of Opulence. This is not to be confused with the Forsaken expansion itself, since the same name is probably where most of the confusion came from.
Bungie announced that the Annual Pass content would become free for any Forsaken expansion owners on 17 September 2019. Now, since the Complete Collection of Destiny 2 includes both Forsaken expansion and the Annual Pass, it will become cheaper since it no longer charges for the latter.
Considering some people bought the Annual Pass recently, some blowback was unavoidable with this announcement. One part of the community is asking for refunds and Bungie have directed them to reach out to retailer support. Some people did, with various results as Blizzard apparently helped those who purchased the game recently but other players reported their efforts to be unsuccessful.
Whatever the result could possibly be in your case, we would strongly suggest you don't go for the Forsaken Annual Pass purchase now since it can only give you a headache through back and forth messaging with Blizzard's support or you might end up wasting money in case you give up.
Simply owning the expansion will suffice. Meanwhile, the potential new players will probably fare the best if they just wait for the release on Steam. Destiny 2 will be free to play then, with a few restrictions regarding Shadowkeep content and some of the Forsaken content.
In case they like the game enough, they can simply purchase the Shadowkeep expansion which will include all the previous content, including expansions and annual pass.