Thanks for bringing this up. There are a few things for which I want to put my thoughts on record.
First up is whether there has been a change in closure policy. The answer is no, there is no official change in policy (there has been none since 2016, even though we have tried a few times). I will also put it out there that if there is any such change in policy, it will not happen behind closed doors. The way we work may seem opaque at times, as if something is brewing behind the scenes, but I reassure you that none of us have dared to even discuss closure policy since 2017, not even in private moderator channels.
However, the guidelines for closure are subjective, and on several occasions it has been argued that they will always be subjective, i.e. "I know it when I see it". Therefore, the exact application of the policy to questions on the site will depend on the individuals who implement this policy. It is not surprising, then, that since the recent election, you (and others) feel that there is a slightly different vibe on the site. It is not just moderators; I notice that as the core members of the community change over the years, the general propensity for closure waxes and wanes.
That brings us to the next point, which is the general idea of how lenient one should be in closing questions. This is a topic which every SE site struggles with, and it is not a black or white thing, there are many shades of grey in between, and everybody has a different opinion on where we should stand.
I believe that (for the most part) we err on the side of leniency, and indeed if you look through my meta posts and site comments, you will find many instances of me arguing to not close questions. I am happy to provide some numbers on how many questions we mod-close. In the last 90 days, between jonsca, Loong, Martin, and myself, we have closed 162 questions. In the same time period, there have been 2753 questions, 1355 of which were closed. So, we are only responsible for ca. 12% of closures, and in my experience, the vast majority of these are for photos of homework. Of course, this number will be slightly biased by the new moderators, but I don't have the energy to address this in detail now.
Nevertheless, it's clear that you think we (or some of us) are still being too heavy-handed. So, what can we really do when there are differences in opinion? One way is to say that we have executive power here and that you had better agree with us, and too bad if you don't like it because you elected us for life, but that doesn't quite get us anywhere.
So, all I can really offer is my own opinion. I personally think that as it stands, we are not being overly trigger-happy with the close hammer, and I leave it to the rest of the community to judge whether this is the case. But, I will also try to keep an eye out for it in the near future (in the last few weeks I have been very busy with real life, so haven't been able to monitor the front page as closely as I would like to). And if I ever feel that things are being unfairly closed, I will complain about it, just as I have in the past, as anybody who's been here long enough will attest to.
Finally, there are individual cases which you have brought up, one of which is my doing. I will just say that I stand by my original decision, because the wording of the question was very unclear. Even putting aside the issue with the "something that I don't know" line, which the first comment adequately pointed out (so you cannot really say that there was no feedback given), it's not clear whether they are asking about how the crystal structure affects the magnetic moment, how the magnetic moment affects the crystal structure, or both. Furthermore, it's not clear whether they're asking specifically about the quoted text, or more generally about any relation between crystal structure and magnetic moment.
But, closure is not the be-all and end-all of a question. Closure is meant to provoke editing and improvement of the question, such that it can be eventually reopened. The unilateral moderator close vote is no different from any other close vote in this respect. Furthermore, if anybody disagrees with it they are free to cast a reopen vote, as you already did.
Of course, sometimes it doesn't pass through the reopen queue successfully, but that is not my fault for closing it. It just means that, as judged by other members of the community, it should stay closed (even after editing), which in fact suggests that I might actually have made the right decision in closing it... What I will note, though, is that that in this case, the decision to not reopen was made by andselisk. I think that as a moderator, stepping into the close/reopen queues is a risky thing, and I personally never do it any more, so I will have a brief word with andselisk about it.
For what it's worth, I've also gone through all the questions which andselisk links to in their answer, and I think that the closure in each case was fully justified. I think some of them deserve to be reopened based on edits that have occurred since the closure, but as I said earlier, that does not reflect a problem with the original close decision.
