I can provide some possible reasons for this phenomenon on Snapchat. However, it's worth noting that app features and behaviors can change over time, so there may have been updates or changes to Snapchat since then.
Caching and Synchronization: Snapchat, like many other social media apps, uses caching to improve performance and reduce server load. When you add someone as a friend or someone adds you, this information is cached on your device to quickly show you the updated friend list. However, when someone removes you as a friend (defriends you), the cached data might not be immediately updated, and that person may still appear in your friend list until the cache refreshes.
Server Delays: It's possible that when someone defriends you, the information takes some time to propagate across Snapchat's servers and databases. During this time, the person might still appear in your friend list until the servers catch up and synchronize the changes.
Bug or Glitch: Technical issues can sometimes cause unexpected behavior in apps. It's possible that the appearance of defriended users in your friend list is a bug or a glitch that Snapchat developers may not be aware of yet.
User Error: Sometimes, users might misunderstand certain actions on the app or accidentally remove someone as a friend, thinking they had previously added them. This could result in situations where someone who defriends you might later re-add you, causing them to show up again in your 'added friends' list.
Privacy Settings: Snapchat allows users to customize their privacy settings. It's conceivable that someone who defriends you changes their privacy settings to restrict their profile visibility, which might cause their name to reappear in your 'added friends' list.
If you notice this happening consistently or encounter other issues with the Snapchat app, it's a good idea to reach out to Snapchat support or check the app's support page to see if there are any known issues or updates addressing the matter.