This question already has an answer here:
I just noticed that six out of the seven questions I've asked here over a six month period were all suddenly down-voted today.
Is there a formal SE term for this phenomenon?
My only question not suddenly down-voted in this block is Is the object in “Eighty-six forty-five.” a proper noun?.
EDIT: Because my question is closed as duplicate I can't post an additional answer, so I will add this here.
It seems there was more down voting to be reversed than mentioned in the accepted answer. On 2017-09-07 an additional
+16 was added to my reputation:
The original correction: