Do you think this was some side effect of the Longevity Dial thing, or Shen Wei doing something one of those times Zhao Yunlan slept? Shen Wei must've known about the defense against personality switching, since he said "Anyone but you is susceptible".

My utterly unscientific theory is that when Shen Wei he fixed Zhao Yunlan's sight, he also in general dealt with the dark energy 'corrosion' that he kept going on about - he didn't remove it but he tweaked it, and Zhao Yunlan now has some 'tamed' dark energy in his body which helps him in situations like that.

But even if that's not how it works, I personally prefer to think he did it during the Longevity Dial exchange, rather than creepily doing stuff when Zhao Yunlan is asleep and without his consent.