It means the person who runs that instance has an Operator Pass. We're building a free list of Fluxer instances, and once it's live, a listing whose admin has a pass will have a line of text saying so. The list isn't out yet, and how it works might still change.
Does the mark mean Fluxer vouches for the instance?
We don't vouch for any listed instance, with or without the mark. We check every listing against the same rules, and each instance's admins moderate it, not us.
Why is it a line of text and not a badge?
A badge or check mark next to an instance's name would look like Fluxer verified that instance or runs it. A line of text on the listing says what the mark means, and it's only there to thank the person who runs the instance for supporting Fluxer.
Does a pass move an instance up the list?
No. A pass never changes where an instance shows up on the list or how big its listing is. Any instance that follows the listing rules can be on the list for free, without a pass.