Revelations from Patch 6.5: "Growing Light", Part 1

[Zero-ELEC]

Unrelated MSQ answer

Zero dropped Golbez' Memoria crystal into the newly-formed Zeromus' cloud during her ineffective attack on it back in the ending of 6.4, and in 6.5 2/3 of the Lunar Subterrane is actually walking through his memories. It can be deduced that the crystal broke apart and Golbez (or at least his memories / aether) was subsumed into Zeromus, or his aether was just free-floating down there until we walked through said memories. The latter seems... less likely to me, but who knows.

The Baron part of the Lunar Subterrane is framed as the Warrior of Light and their companions finding the memoria. We see the complete crystal rise and glow in-dungeon and I believe in the post-dungeon cutscene. The memoria appears intact.