You want to download/install an old version of Snapchat on your iPhone (e.g., because the new version is slow, has bugs, or you dislike the UI changes).
You're a developer and want technical guidance on how to build something that emulates old Snapchat behavior.
Allow users to toggle between the current Snapchat UI and a simplified "Classic" interface reminiscent of Snapchat ~2014-2016.
: The massive 2018 redesign merged Friends' Stories with direct messages, which many found cluttered compared to the original separate tabs.