It had been renamed Infinite Light in V18.104.22.168. Due to community demand, the ability was again renamed to Final Spark in V22.214.171.124.
"Final Sparkle" was likely a reference to Marisa Kirisame's upgraded spellcard called Final Spark.
This ability bears close resemblance to Final Flash, an ability used by Vegeta in Dragonball Z. They both begin charging this ability with their arms pointing out to the side, and finish it with their arms pointing forward. The names and shapes of the abilities are also similar.
Lux's taunt about power levels is a reference to the manga/anime Dragon Ball Z.
Lux's taunt "In the name of Demacia, I will punish you!", is likely a reference to the manga/anime Sailor Moon.
Lux's movement quote "I love it when a plan comes together" is a reference to the A-Team's Colonel Hannibal Smith's favorite catchphrase.
Lux's joke "Double Rainbow? What does it mean?..." and the follow up joke "Well, a 'double rainbow'..." is a reference to a well-known YouTube video where a man severely overreacts to seeing a double rainbow.
In the polish client, Lux's joke "Light? I carry it in myself" is a reference to a line from a polish song "Light, you carry it in yourself" and is sung in the same melody.
The quote "Shhh! I'm charging my laser..." is a reference to the Shoop Da Whoop meme.
The splash art for Sorceress Lux resembles the character Marisa Kirisame from the Touhou Project, when Marisa is shown in her navy-blue dress and riding a broom (or a vine) in memorable versions. Also in the splash-art of the Sorceress skin, Lux is in front of a full-moon, likely a reference to Touhou 8 (Imperishable Night), the first game in the series to have clearly depicted Marisa on a broom, where the story revolved around retrieving stolen full-moon.
Spellthief Lux is another reference to Marisa Kirisame, who also steals spells.
Imperial Lux is likely a homage to the Star Wars universe; bearing a strong similarity to Admiral Dodonna of the Old Republic.
Imperial Lux is often compared to the visual look of Street Fighter's M. Bison who has a fairly similar appearance.