There are a number of interesting and disconcerting totals here that show just how much Destiny 2 has lost over the years, both in terms of free-to-play and paid content. And past that ...
Destiny 2's Revenant Act 2 was turbulent due to bugs, leaving fans upset with lower morale. Bungie needs to win back fans by unvaulting all removed content, addressing their complaints.
However, Bungie also vaulted Leviathan, its two raid lairs, Crown of Sorrow and Scourge of the Past from Destiny 2 itself, so those seem like options to be “reprised” from the content vault.