Joplin does not encrypt notes at rest. Only data being synced is encrypted; when it gets to its destination it’s available unencrypted in an SQLite database. Any program running on your computer can read your Joplin notes at any time. The developer has come out against implementing encryption-at-rest many times throughout the years. Their suggestion is that you use another form of encryption, like veracrypt. Notably, this makes using Joplin with encryption-at-rest impossible on iOS.

https://discourse.joplinapp.org/t/requesting-encryption-of-l...