Not sure if error or what.

So I'm not a subscriber, can't afford, but there are a few hentai on this site I can still view.

For example: Karma

Well, it's a western comic so I'm not even sure if it's unlicensed or not.

For all I know, gy (the artist) could be a user of Fakku.

Not a bug. Probably intended to be free to read to grab an audience for the artist.

I think all chapters with the western tag are free to read at the moment

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Not true. Doxy's new works are not.

My bad, you are right...everything with western tag except Doxy (I didn´t pay attention to the subscription banner)

Most likely this. gy's Karma was added to the site kinda before he became officially affiliated with Fakku (since his latest release is behind a paywall I believe).