The change means that any episodes of The Simpsons originally aired before 2009 will now provide the option to be watched in their original 4:3 ratio rather than the hi-def 16:9 modern shows have adopted.
“While all episodes in the series were initially provided on Disney+ in 16:9, the goal was to provide both the original 4:3 aspect ratio and the 16:9 versions, providing a choice as to which format to watch, especially for our super fans,” Disney’s Joe Rice detailed in a blog post.
“The best user experience would be achieved by treating 4:3 and 16:9 versions equally, supporting all Disney+ product features and content interaction mechanisms, while adding a new app feature — choice of aspect ratio.
“Existing features including Continue Watching, Watchlists, and the ability to binge by auto-playing episodes in sequential order had to be maintained regardless of the current aspect ratio mode. (Given those features wouldn’t be supported were the 4:3 versions to be added as standalone bonus content, that option was discarded.)”
Disney confirmed back in November 2019 that it was addressing the issue.