Fixed an issue where players progressing backwards in Root of Nightmares to the hidden chest location in the Scission encounter space would see Cavum of Nezarec in a T-Pose and be unable to defeat it.

Source: https://comicbook.com/gaming/news/destiny-2-season-of-the-deep-update-patch-notes/

Known as the Final God of Pain, Nezarec appears in 's Root of Nightmares raid as the final boss of the destroyed Pyramid Ship players infiltrates to stop this Disciple of the Witness.

Source: https://screenrant.com/destiny-2-root-nightmares-nezarec-boss-fight-guide/