Do we really need another round of what the souls of the third sacrifice were in debate? How does animals and plants make any sense with how Zodiark operates. Or at least with how little we know of how he operates. You'd think they wouldn't want any souls stuck inside of Zodiark. Since those souls wouldn't be able to return to the star.
Unless you play soul switcheroo every now and then or idk maybe just not offer up souls to a primal who even if it is " "Just a tug" " when it may or may not come to tempering of his summoners. Just a tug gets added to with each summoning I assume. It's easy to assume or say the 3rd sacrifice hinted at only wanting to release the 1st sacrifice which is kinda yikes about those who we again we are to assume that those who were part of the second were volunteers. You know if the 3rd wasn't to just get the 1st set out and get both of the 1st two out. Which again still leaves you with souls trapped inside of a primal regardless of if that soul was a person, animal or a plant. For those who wonder how Zodiark gets painted as a blood God this is how it happens. He also can be easily made into a Staple's easy button for any hardships the Ancients might come across down the road. I.e if they kept him around since you know for all the gen public and the convocation know he's the only reason the Final Days stopped. They also had him change and keep in place how some of the aether currents ran which we're just now finding out what reversing that change means and looks like.
So you either paint post Final Days but pre-sundering Ancients as people who only care about old, thick and chunky Ancient souls and not actually caring anymore about souls not being able to return to the star regardless of any differences they might have. Or you paint them still caring about that and having just as much uncomfort about those different newer souls being stuck in there and needing at least a fourth sacrifice of something to get the newer souls out. As just letting them stay inside Zodiark wouldn't make much sense otherwise.