Ryu felt his Control take hold of his Qi, refining it and saturating it with his Chaotic Silk Meridians with it.
Last time he went through the Qi Refinement Realm, Ryu hadn't had Chaos Qi and had instead worked with normal neutral Qi. The difference was clearly akin to night and day, but that also posed a great challenge for his Control.
Trying to impose his Dao Heart onto normal qi was of course, very easy… but to try and do so with Chaos Qi, one of the strongest qis in Existence? That was a different matter entirely.
Until now, Ryu's use of Chaos Qi was always a series of borrowing actions. When he needed Chaos Qi, he communicated with the Chaos Plane and took the Qi in for himself.
However, doing so was obviously less efficient than having qi directly in his Meridians, and there was also a lag in qi control as well.
Of course, this was negligible, especially when Ryu's usual levels of qi control. But it was something that was noticeable to Ryu.