Han Solo's confrontation with Greedo at the Mos Eisley cantina has been a point of contention for fans for decades now, due to the fact that the scene seems to change with every new edition of Star Wars: A New Hope, beginning with the 1997 Special Edition, which saw Greedo shoot first where it was originally Han.
Paul Duncan, author of The Star Wars Archives: Eps I-III: 1999-2005 recently filmed an unboxing, during which Duncan revealed how specific Lucas had been in his planning of the now-infamous cantina scene. He explained, "I found a document... that actually says that on frame 52, is the approximate start mark for Greedo-- for his misfire. And frame 57 -- five frames later, which is less than a quarter of a second -- approximate start for Han returning fire."
Future editions of the film presented audiences with even more changes to the scene, all of which had been included by George Lucas himself. The most recent change debuted on Disney+ and featured an extra shot of Greedo inserted into the scene, uttering what has been transcribed as "maclunkey" before firing first.
The scene continues to be controversial among the Star Wars fanbase, many of which maintain that Han shot first-- an action that some argue helped to define him as a rogue, and by extension, better defines his transformation across the original trilogy.
Source: Gizmodo