I don't really understand reddit's angle here... Why would they provide zero cost API access to an app, as long as the developer of the app isn't making a profit? Are they trying to act like that was the issue they had with these third party apps? That they e profitable?
How does it make sense for them to allow an app for that reason?
That's what Narwhal dev had publicly offered previously, there's no firm confirmation that's actually the deal and I'd be a little surprised if it was.
I think Reddit chose to give them a sweetheart deal because they're the worst competitor app, the dev had been least publicly critical of the API changes, and Reddit wants the PR value of an example case "proving" their API changes weren't maliciously anticompetitive towards third-party apps.
The fact that Narwhal has struck a deal now allows Reddit Inc to say "see! we do work with third party apps; it's not that we're bad, it's that RIF and Apollo are big meanies who won't cooperate!"
It looks strongly like one of two things has happened - either Narwhal took the knee and has accepted absolutely abysmal terms in order to remain in existence, or Reddit has offered them a better deal in private to keep them afloat - solely to use them as a PR example case.
The only thing that seems unlikely is that they're working under strict terms of the published agreement, otherwise IMO costs to users are functionally unfeasible.
Which raises another question: are analysts and investors so stupid that they can't read between the lines? Because this looks like using a bucket to douse a five-alarm fire.