I believe they used power delete suite

I saw a few people editing all their Reddit comments/posts with an explanation as to why the info is gone and they also gave a link to where they could find their content reposted on Lemmy. Thought that was pretty clever.

Once upon a time there wasn’t a good Reddit app for iOS with usability and accessibility like the rest of Apple’s ecosystem. Then comes along Alien Blue, which kicked ass. After a while, Reddit buys Alien Blue and ruins the UI. Apollo then clones Alien Blue and starts improving on it. Apollo quickly became the only way I would use Reddit on my phone. It was a better client than anything Reddit has come up with on their own - I’d wager their official app is unusable for many people.

Memmy is great alternative to Apollo for iOS.