https://www.polygon.com/2018/6/1/17417808/destiny-2-faction-rallies-exotic-rewards

Faction Rallies was removed from Destiny 2’s rotating events list in March. It’ll make its triumphant return on June 5 shortly after Bungie finishes its livestream reveal for the game’s second year of content. This new Faction Rallies event will still involve pledging yourself to one of Destiny’s three factions — New Monarchy, Dead Orbit and Future War Cult — but players can earn better rewards through more interesting gameplay.

In the latest edition of This Week at Bungie, community manager dmg04 detailed the upcoming Faction Rallies changes. Players can only pledge to a single faction per account now, rather than pledging individually based on each character. If you want loot from all three factions, don’t worry too much; Bungie announced that it will host three Faction Rallies this season (before old rewards cycle out in favor of new ones).