Based on player reports, the Dragonflight Pre-Patch may have reset all players Great Vault Loot pool.
Thanks to Sanghelios for pointing this out to us.
Great Vault Loot Pool Possibly Reset
Players have started to report that this week’s Great Vault only contains loot from bosses that you killed last week. If you only defeated Sepulcher of the First Ones bosses, you’ll only have Sepulcher of the First Ones loot, even if you killed Castle Nathria or Sanctum of Domination bosses before.