Does downvoting an answer qualify as divisive and harsh speech? In a comment to an answer on this site I saw this:

To the folks who insist on downvoting, please note that downvoting is
extremely unhelpful and actually qualifies as divisive and harsh
speech.

Do others agree? Does downvoting an answer necessarily qualify as divisive and harsh speech? I've thought of it as a form of feedback. Of course, if it is possible to elaborate and provide more constructive feedback then by all means...
Does downvoting violate the precept on correct speech?
Divisive speech is speech that sets people up against each other. Divisive speech sows the seeds of conflict and suffering.
A typical example of divisive speech is telling one person or group of people something negative about another person or group of people, usually in private. This gives one side a reason to generate aversion towards the other side.
Harsh speech is rude or offensive speech usually directed at its object. For example when you disagree with a person's understanding of Buddhism you tell him or her that he or she is an idiot, completely confused about right Dharma etc.
Harsh speech sows the seeds of conflict and suffering by giving the other person a reason to generate aversion towards you and your opinions. This is especially dangerous and harmful if your opinions are actually right and beneficial, because it creates a reason for the other person to hate what's right and beneficial!
In both cases Buddha made exception for the senior bhikkhus to censor and reprimand the novice bhikkhus. He compared it with a surgeon causing temporary pain to a patient for the sake of long-term benefit. He also said, not speaking up when someone is wrong according to Dharma is by itself a problem, because it enables the wrong behavior or understanding to endure.
Finally, Buddha said that when saying things that are beneficial but unpleasant to others we must have a good sense of timing and tact, to say it in the most acceptable and the least harmful way.
From all the above we can understand that negative feedback is acceptable and even encouraged in Buddhism, provided it's done properly to make sure it lands well.
I don't think downvoting can qualify as divisive speech, because we are not (privately) setting up people against each other. Someone may say that it creates the reasons for other people to dislike the downvoted answer, but that would only be true if the answer could not be upvoted by someone else who finds it right and beneficial. At the end, it's the cumulative effect of multiple votes that matters, not a single up or down vote.
As to whether downvoting qualifies as harsh speech creating a reason for the author to dislike the downvoter, I think this would be true if the votes were not anonymous. However the way it is done on this site, no one can see who has voted something up or down so unless you tell the person you did it, their frustration does not have a specific object. This way it serves as a signal that their answer was not 100% acceptable by all readers which by itself is useful feedback IMO.
Then again, I think this falls into the territory of &quot;the right timing and a sense of tact&quot;. Sometimes a gentle comment is more appropriate and sometimes a downvote or even a moderators flag is the right way to go.
Just my 2 cents.