Less materials per alts

Is it normal that after the 7th alt in T3 they started giving me less materials with rest? Have you felt something similar?
when I was only 6 alts they gave me 860-900 blue stones, now with the 7th they give me 630-660. I’ve been like this for a week so it wasn’t an isolated case.

This just from chaos dungeons.

How do you even get 860-900 per t3 alt? Assuming it is 1370, you should only get that amount if you hit the golden gate that has the stone in it. It is around 600-700 for me consistently.