I've found this:
But I think that's correct this way, right?
This would also cause some topics/posts to be owned by the Guest pseudo-user.
Maybe this could fix it:
It appears now as a Guest's post.
The user's record is gone, but the post's record still contains the user's uid number. So the post could appear attributed to "Guest 2839" instead of only "Guest" for all past accounts.
(Allow users to delete or "close" their accounts · Issue #1284 · NodeBB/NodeBB)
@julian Perhaps, instead of “Guest 2839” for a user who deleted the account but not the posts, something like “Former 2839” or similar.
It‘s more respectful than “deleted” for former users that chose to go and weren’t spammers, but on the contrary wrote valuable posts that were kept.
Of course, in the case of spammers, account and posts are all deleted, so no need for “deleted user”.