A lot of Marvel characters go through some significant changes over the course of the most recent Marvel Cinematic Universe films, but possibly none go through quite such a radical transformation as Thor. Even before Avengers: Infinity War starts Thor has become the de facto leader of Asgard, which as a place no longer exists. Not only has his status changed greatly, but he's also changed physically, having lost both Mjolnir, and his right eye.
The eye problem gets sorted out somewhat quickly in Avengers: Infinity War, as it seems Rocket has a spare one lying around, something which doesn't even seem odd considering what we know of Rocket, but it appears that, at some point in early development on the final two Avengers movies, there was no plan to give Thor a new eye, which would have resulted in the Endgame version of the character still wearing the eyepatch, along with transforming into his new "relaxed" character. Check out the look in Endgame concept art below.
"
I for one was more than a little bummed that Thor's eyepatch was replaced so quickly. I thought the look worked pretty well on its own, and it made sense to give Thor this visual scar reminding the audience of the events of Thor: Ragnarok. It also was something of a connection to his father, who also only had one eye. Since this is how Thor looked the last time we saw him, it certainly made sense to draw him that way, especially if this art, posted to Imgur by user CooperHood, was created early on, before scripts were completed. As simple as the method for replacing Thor's eye was, it's still something that you have find and be sure it works.
Looking at these pictures which show both the chill, beer drinking Thor, and the ready for a fight version, I'm even more annoyed that they gave Thor a new eye. These images look great and I think would have really worked for the character.
Interestingly, the eyepatch in question wasn't actually real. While they tried to make the eyepatch work physically, Chris Hemsworth has said it kept falling off, and so the eyepatch was actually created digitally. One wonders if the fact that the eyepatch was such an issue was part of the reason it was replaced. It takes time and money to create any digital effect and having somebody build a digital eyepatch through two entire films might not have been seen as the best use of time.
Of course, if this had been Thor's look in Avengers: Endgame, then it would likely still be the state the character would be in now. We'd be going into Thor: Love and Thunder was a one-eyed Thor, but instead, he'll have two eyes, even if he's not entirely sure where one of them came from.
Maybe, by the time of the next movie, Thor will have figured out a way to make his two eyes the same color.
