Going back a few pages here to answer this:

Quote Originally Posted by Theozilla View Post
And where was it stated that the new life Zodiark cultivated/renewed before the Sundering was less powerful/had less aether power than the average Ancient? I see that stated a lot, but I can’t recall where it was stated in the game itself?
It comes from Patch 5.3 with the Convocation Crystals. The Crystal for Emet-Selch reads:

Gone is the brilliant radiance of life, replaced by the sickly glow of malformed creatures. Is this to be how it ends? For we who loved the star with all our being? No. I will not suffer it to be so.
That said, there's a chance he's talking about life post-Sundering. The Convocation Crystals seem to cover quite the range of time, with Lahabrea talking about how they need to rewrite the laws of creation which would be before the summoning of Zodiark, and Pashtarot talking about how salvation came at a great cost which would be after the summoning of Zodiark. Most notably, Halmarut has this to say in their Convocation Crystal:

Behold, my friends.
Embraced by the earth and caressed by the wind, vibrant life flourishes. All is right in creation.
We don't know how gifted Halmarut was at seeing souls, if at all, so there's a chance they might not have noticed how malformed the new life was. Either way, this quote definitely happens after the second Amaurotine sacrifice and before the Sundering. As for Emet-Selch, his quote could be before or after the Sundering. Since he was so incredibly gifted when it came to looking at souls there's a chance he saw the new life created by Zodiark as malformed where Halmarut didn't, or he was talking about the Sundered lifeforms which we know he thinks poorly of. It could go either way.