FXX isn't just resurrecting old episodes of The Simpsons during its week-and-a-half marathon. It's also making us relive one of our more painful memories: last decade's labored transition from standard definition to HD programming. The network has made the inexplicable decision to broadcast the show in a 16:9 aspect ratio even though the majority of episodes are in 4:3. The show didn't switch to HD until 2009, in season 20, so most of the episodes on FXX are zoomed in and cropped. That means it's not just ugly — you're missing the show as it was meant to be seen.
The cable network previously announced that the Simpsons episodes had been "digitally remastered" with an "HD update" to 16:9. But it seems FXX thinks turning something into HD is as easy as cropping off the top and bottom. The network also went through and color corrected each episode, which longtime fans with keen eyes have likely noticed. For its part, it seems FXX has been careful with how it has cropped the episodes — it's not a simple crop of the middle part of the image. When possible, the network adjusted the crop to keep the most important part of the image, as you can see in this Reddit comparison of pictures from the FXX broadcast and episodes with the original aspect ratio.
And, no, switching to the SD feed doesn't fix things: the content comes through letterboxed. Oops.
Correction: This article originally included a cropped image of a shop named "Sneed's Feed & Seed" from an episode in season 11. The image was provided by Indie Wire. That episode has not aired yet — it appears Indie Wire cropped the original image itself rather than pulling it from FXX's broadcast, which means the image was not an accurate representation of how the network has cropped the show. We have provided our own image comparison from "Lisa's Date with Density," an episode from season 8. We regret the error.