The memeory revival drug is illegal. I don't see how Qingzu could have purposefully had it if she had been reborn in the meantime, and still kept her current position. And she's not important enough for the Vidyadhara Preceptors to have them secretly dose her with it.

So her age is a bug, yeah... maybe she's on the longer side of "average" life expectancy, like Jingliu is for native Xianzhou. I mean, after all, someone has to average out that one gal who rebirths every few months or so.