The votes that you are referring aren't "serial downvoting" b/c the referred questions didn't include any research effort, they were very short (meaning unclear / brevivity should not sacrifice clarity), and they were not viciously choosen.
In new tab of the main site Questions page I found a bad question, as the OP is a >10k rep user before taking any action I took a look to the OP profil. I found that they have several 0 votes questions, these questions are of the same "style" (no research effort, very short). Then I reviewed one by one all the OP questions that had 0 votes, 0 answers and very low number of views (38 questions). I choose to downvote only the oldest b/c they deserve be downvoted and b/c they were abandoned questions.
It's worthy to note that two of the downvoted are five and three years old and that when they were downvoted have not been edited and hadn't any answer.
Today a couple of them were edited and all were self answered.
Regarding the way to "appeal" the downvotes, there isn't a way to "appeal" downvotes b/c they aren't ♦ moderation actions, but you can invite me to chat, or as you already did, post here in meta. I reserve for my self the right to answer / abandone unpolite posts/conversations.