I have a strong suspicion that most if not all of the low-quality, bad-faith trolling questions about the Holocaust and Jews are done by the same person using multiple user accounts.
A lot of questions are about the same, or very similar topics. Of all the questions that I've helpfully flagged as being rude and abusive, many of them are about the Holocaust, and many of those that weren't instead were about Jews, or Nazi Germany.
A lot of the bad-faith questions about the Holocaust are similar in length: see the research in Should we increase the required question length of the quality filter to deal with Holocaust trolling?. This is despite the fact they involve different user accounts.
A lot of bad-faith questions about the Holocaust use similar phrases, telling other users to refute them, or saying that the Holocaust denial can't possibly be real (the person pretends to not be a Holocaust denier to increase the mockery), even though they involve different user accounts. Here's a sampling of these kinds of phrases:
That can't be true. Refute this.
This appears to be Fascist. Refute it. Do not allow these memes
Refute this article please. Zionism depends on it.
This must be true because the holocaust is real. Most certainly 6 million jews were gassed at Auschwitz starting in 1939. I just need to confirm this fact to make sure I do not appear a holocaust skeptic.
Is this a holocaust denial website?
I nean of course right. Why would there not be. Scientific evidence. Are witnesses scientific.
This must be refuted, it cannot be allowed.
Wonder if any of this is true.
Please let me know if you need clarification.
Questions that are almost exactly identical are posted by different users. For example, Did Soviets build a fake chimney in Poland? is by https://skeptics.stackexchange.com/users/52757/user52383 (why does 52757 not match user52383?), while https://skeptics.stackexchange.com/posts/45513/revisions was by user52603.
Users who have asked bad-faith questions about the Holocaust or about Jews might have a similar pattern of which Stack Exchanges they're members of. According to Limited in what I can do to investigate a suspicious question, the user who posted a question about Jews in the USSR was a member of Skeptics, Biology, Meta, Mi Yodeya, and Philosophy, while the user who posted a question about Auschwitz is a member of Skeptics, Biology, Meta, Mi Yodeya, Philosophy, and Politics.
The number of users involved in asking these questions is very large: there's user52308, user48066, https://skeptics.stackexchange.com/users/47060/a25bedc5-3d09-41b8-82fb-ea6c353d75ae, user45688, https://skeptics.stackexchange.com/users/28725/jacob-blaustein (note: this question involved anti-African-American bigotry, not anti-semitism), user42171, user40243, user40239 answering a question by user40238, user40193 and user40190 and user40188 answering a question by user40185, user37556 and https://skeptics.stackexchange.com/users/31326/d-j-sims asking questions that only differed in that one said "Is there a way to refute this image?" and the other said "Can you refute this image?", user37064, and so on. Unless we're under attack by a battalion of nazis, there has to be some sock-puppetry going on.
Is it possible for the Stack Exchange software to improve its detection of sockpuppets without causing damage to legitimate users?
I checked the meta stack exchange for sockpuppets, but most of them were about voting rings, rather than problematic people trying to evade bans.