Hey Entity,
It’s only the plugin — the website works fine.
But downloading every single asset manually and rebuilding the material instances myself is a lot more work. Also, depending on the asset creator, the results can vary compared to using the Fab plugin import — at least in my experience.
Most of the time, when I open the Fab feature in the UE content browser, I have to log in through a browser window to confirm my Fab/Epic account. That process usually fails and gives me an error message. Then, I get a pop-up offering to reload the plugin — which most of the time leads straight into the infinite captcha loop.
At first, I thought it was an invalid web token or some local cache issue on my side. But I’ve tried everything, and I still can’t explain why this is only happening to some users for weeks now. 
Also, I already saw forum posts about this infinite captcha loop at the end of last year — even back then, it seemed to affect Fab plugin users specifically. No solution back than.