Are requiem mods permanent?

I'm curious to know, are requiem mods truly permanent in nature? Is there any possibility of reversal or expiration once they've been implemented? I understand that these modifications can significantly alter gameplay, but I'm eager to learn more about their longevity and potential implications for the future of the game. Can you provide any insight into the permanence of requiem mods and what players should consider before making such changes to their experience?