To just the author and mods, unfortunately we cannot support this yet, as we don't have a "post author" pseudo-group. That is a good idea, though.
We did accomplish this via nodebb-plugin-support-forum, you could try this and see if it still works?
Hello, I'm new here, just about to start using NodeBB after using flarum for around a year.
I was wondering I keep seeing this 'login to view' icon as above, is this a plugin? Or something only implemented on this forum only? .
This is a setting in the ACP.