I’m a long-term user of Day One, the premier journaling app for iOS/MacOS. In 2017, Day One introduced end-to-end encryption on user journals (which I use), to protect the journal data synced with their proprietary service (that became mandatory after Dropbox sync was dropped in v2)
This is a companion discussion topic for the original entry at https://www.funkypenguin.co.nz/opinion/2018/05/11/post-mortem-review-day-one-sync-outage-and-private-data-exposure.html