all three, or one of the three?

How do plan to define 'scandal'? On Manifold, insider betting/trading is often seen as a feature, not a bug, since it brings information to light faster. Insider trading could be reported on by Matt Levine or others, but not necessarily regarded as a scandal.

For example, if Matt Levine had created an account and bet YES on the market about him linking to Manifold (and then linked to Manifold), that would widely be considered the way things ought to have gone.
Will Matt Levine link to Manifold by 2024? | Manifold

That said, there are a number of shenanigans that could be seen as slightly more 'scandalous.' For example, sometimes there is profit manipulation in one market order to rig another market (usually related to Manifold Leagues), and there have been penalties for doing this. However, the bar for an insider trading scandal is pretty high.

There's a "whale fight" here over whether or not a prominent user will break their betting streak:
Will @firstuserhere break the 271 day+ streak in 2023? ($500M subsidy) | Manifold
Of course, this is highly susceptible to manipulation, but that's part of the game of it.

@Charlie The glib answer is that manifold is as much betting on interpreting the question as it is about divining real world events.

But on a deeper level, markets are about using signals to reach consensus. Part of this question is about whether manifold is important enough that anything that happens on it is reportable to the outside world. If, as you say, the shenanigans are part of the manifold experience, then that would raise the bar on what is notable enough to be scandalous and should be factored into the be analysis.

You are right though. There is a certain amount of vibes based analysis that goes into determining if something is scandalous. As far vibes based questions on manifold go I don't think this one is too bad. I tried to limit it by offloading the determination to the admins & the news but as they say "it not perfect system".

While on the topic of sources, Matt Levine is on the list more or less as a joke. As good as his column is, he provides analysis and commentary based primary reporting. He is very diligent about linking to sources. Should a "scandal" or even a scandal happen I expect it to be reported by the admins or an outside news outlet first.