I’m not sure? Did you download the actual file or are you just looking at the compressed preview on drive?
It looks pretty sharp on the file on my computer. I did have to do some funky things to get the new Leia to blend in so it looks (mostly) like it belongs with the surrounding art, because that was just a photograph which I took from the 04 DVD cover. I did this because the image of Leia on the actual Struzan art is clearly not the Leia from SW and is (I think) the Leia from Empire. So it might look slightly soft in that area, but overall it looks pretty sharp to my eyes. You may notice I also added the Death Star into the bottom right corner, but that blended even better than Leia I think. I did the main design of this some time ago, this final version is just updating the proportions to make it fit a 14mm spine bluray case, but I remember using the highest res version of this art that I could find.