It will be much easier to farm Archivist’s Codex rep in 9.1.5
Maybe you haven't really been playing Shadowlands and you're thinking about coming back, but you're intimidated by the whole process of getting Archivist's Codex reputation.
How to earn reputation with The Archivists’ Codex in Korthia
Relics are a thing of the past.
WoW Archivist: Four classic ideas Battle for Azeroth should bring back
To me, Legion was far more nostalgic than the transparently nostalgia-driven Warlords of Draenor.