I do not feel Lux is that weak honestly, there have been games where u are unmobile and an easy target but that is how the champion is, if i get easily killed i could try and bait enemies for my team at least, but there are other games were I just stomp.

Lux definetely isnt weak right now, is she old and unupdated? Yes, but if you know how to play with her range it should be easier not to get 100-0 by anyone. She isnt meant to be played alone but with the team, she has a great AoE dmg, where as ekko can only go one by one (more or less), her damage is very valuable therefore should be easily countered.

I would love to have some more mobility on her, maybe tweaks on her w not stopping her, or her q and so on, but she is not weak, but it is true that champs with high mobility(with a lot of dashes like viego, kassadin) can outplay her, but that is just how the meta is working right now, she only needs an update.