The costs of using the longevity dial are high, but I find it very noticeable that when a member of the team uses it, it's not commented on just what the price is - which I think would be a pretty normal narrative thing to do. (And Li Qian doesn't say exactly what it cost her, either.)

And Zhao Yunlan's slightly crazy readiness to use it on people he met ten minutes ago also doesn't exactly say "it'll cost you half your life" - the man is crazy but that would be a little crazy even for him? I think?

My favourite theory re: Shen Wei ATM is that they thought it would slightly hurt a human to fix Zhao Yunlan's eyes, and Shen Wei could probably totally bounce over that because he's the Black Cloaked Envoy, and then it ended up fucking up Shen Wei more than it would have a human. Because I think that works with Shen Wei's visible surprise after the exchange and everyone's characterisations, and I like the OOPS factor of it. But canon is definitely hazy on this!