Can staff see who wrote a confession?
Other members cannot see the author in either mode. In Hidden mode, reviewers can press Reveal author on a pending confession, and if you set a log channel, the log names the author of every logged confession. In Anonymous mode the bot stores no Discord user ID for it, the review card has no Reveal author button, and the log says Anonymous.
Can members post images?
Only if you allow it, and only in Hidden mode. It is off by default. When it is on, a member can paste one https link to a png, jpg, jpeg, gif or webp image into the form. It is a link field, so there is no upload.
What stops people from spamming it?
A cooldown between confessions, 5 minutes by default and shared with replies, plus an optional daily limit, minimum account age, minimum time in the server, and blocked roles or members. Reviewers can ban an author, for a set time or permanently, and bans work in Anonymous mode too.
What permissions does it need?
Four: View Channel, Send Messages, Create Public Threads and Manage Threads. It cannot ban, kick or time anyone out. A confession ban is kept by the bot itself and blocks only confessions and replies.
What does the bot keep about a confession?
The text and a per-server pseudonym, and in Hidden mode also the author. In Anonymous mode no Discord user ID is kept. Everything the bot stores for your server is deleted when the bot leaves it.