The service returns a 503 after some time. Seems to be happening since a few hours ago. Doesn't matter following a direct link or entering any website through their search bar.

Noted about 5 hours ago as I post this. See:

https://news.ycombinator.com/item?id=27486505

Had a burst of this a few hours ago, then it seemed to recover. Yes, I'm seeing 503 again...