I was voting in Quality Guardian, and when I clicked “No”: And when I removed the thumbs ups notification, it got fixed. My browser is Google chrome.

Did you actually receive thumbs-ups?

Yes. 3 thumbs ups.

Ew, that is strange. Maybe another bug due to the DDoS attack? Does it happen again or was it just a one-time-problem?

It happened again. But then it stopped.