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You Can't Look at Porn on Any Reddit Third-Party App Now
(www.vice.com)
This is a most excellent place for technology news and articles.
Well I know they forced some subreddits go back to SFW if it was obvious the NSFW was just to protest. Maybe that's the case for the subreddit you're looking at?
NSFW means no ads as well.
I also remember the announcement was sexually explicit content won’t be served through the api, so they must have a way to differentiate then.