Lux's base skin ult had a visual change that made it way less satisfying to use.
A while back, I think it was in season 6, Lux's ult on the base skin was visually changed. It went from red to a pinkish-red with white in the middle. This change made it feel incredibly less satisfying to use. Here's a before and after.
Old Ult: https://youtu.be/_SJ8xH2S2SU
Current Ult: https://youtu.be/WBjQ7wRGbLY
Now, I own all the Lux skins, but my favorites are Sorceress (base) and Spellthief (base) and I often find myself just taking a different skin just because the ult feels so unsatisfying now. I've played her since season 5 and there is definently a difference in satisfaction you get from casting the ability, for the worse.
Just watch an lcs video with Lux in it (there are some) and look for when the Lux casts her ult. Which one feels more satisfying for you to watch go off?
I really hope this change gets reverted, as the change just made her feel less unsatisfying and didn't actually change anything else.