Over the past two weeks or so, someone(s) have been searching out my answers which they liked, and upvoting them, say $10$ questions or so, but an automated process reverses the votes. I don't know who the person(s) voting are, but do voters know that if they upvote someone's old answers too rapidly, their votes are nullified?
I myself learnt a lot by going through and upvoting old answers of luminaries whose answers I liked, but never knew that I couldn't upvote too quickly.
The marks don't matter but the deletion leaves an impression as if something shady is going on.