From VG247: “Dataminers have discovered that once all of the runes at Loot Lake are activated, players will be transported to the Nexus to vote to unvault old weapons.
Fortnite Season 8 is drawing to a close and once the volcano erupts it looks like players will be sent to the Nexus where theyll be able to vote on one of six vaulted weapons to potentially bring back to the game. The last time players were sent to this dimension was during the butterfly event.”
Source: N4G PC Fortnite Nexus event may let players vote to unvault a weapon