If you are talking about the effect of the Aizen and Yhwach conversation in cour 1, I will have to disagree
When Aizen played with Yhwach's perception of time, Yhwach noticed this effect, albeit late, so KS's effect must have ended on Yhwach as well
On the other hand, the only thing left is the battle between Yhwach and Aizen where Aizen puts Yhwach under the influence of KS, which I do not object to
If I look at it according to your logic, Almighty is a power that can see even events in the very distant future, such as the death of SK (and we know that Yhwach had Almighty in the past, so he saw must be )
And in the final battle, Aizen's pre-release of KS and the fact that it completely destroyed Yhwach's perception during the battle is further evidence that this happened within the battle
Also The future that Yhwach sees wrong (which is actually true but he thinks is a dream) If you look at Zangetsu, you will see that he is in the same form as Zangetsu who slew Yhwach.However, as I said, Ichigo's sword, which went towards Yhwach who woke up from sleep, was in the form of a knife and a sword (in short, it was in True Shikai form) So I don't think it's just about Yhwach's sleeping part, it's a direct reference to the future where Yhwach dies