The Lux buff was absolutely terrible

It does nothing to resolve her core issues

or the fact that she often doesn't secure kills with her R unless she's far in the game or the mid/AD fucks up. Even then, with how many people (especially higher up) buy Guardian Angel this does nothing for her at all.

or how awful and clunky her kit feels to use.

With the way her kit functions right now all you can reliably do is combo a squishy and hope that under the layers of shielding/redemption they actually die. Fishing for kills, kiting out frontliners, or zoning out areas is really risky because it's so easy to go OOM unless you have blue. Make her W faster and drop the mana cost of her E to 70/80/90/100/110 from 70/85/100/115/130 since the costs are archaic. I guarantee that'll resolve actual issues she had, especially Diamond+, where people actually capitalize heavily on these things.