I think I have reached a dead end where I am not sure whether the issue is the team I manage or the way I manage.
The first months of my promotion to manager went well, but after the 6th month my team are getting increasingly judgmental, verbal, aggressive and frustrated. I initially thought it was only one person who was jealous that I got promoted, but he seems to have infected the rest (others on the team are starting to "agree with him", which is very concerning because he is often just being wrongly judgmental).
I know of two possible sources of frustration:
Senior Management has changed and my team members have much less authority than they used to in the previous years. Decisions need to be documented, approved, and many plans come from above rather than my team members going out independently. My role in this new structure is seen by my senior team members as that of a bureaucrat implementing rules but with minor influence on our overall strategy. The fact that the plans from new management led to negative consequences on a few occasions makes the technical experts on my team openly and aggressively question/criticize every new management decision and even intermediary steps suggested by me. On multiple occasions, I find that criticism to be incorrect and simply cynical pessimism.
There is an unspoken culture of secrecy between senior management and individual contributors. Even I am unaware of some grand level strategies, but sometimes it is unclear what can be communicated and what can't. I believe the ideal situation is that individual contributors just do their work without questioning anything, then management can see how it goes.
Now here's the thing. Personally, I am very optimistic about the new senior management and their overall direction. The minor issues we come across are just due to the infancy of this new thing e.g. like the use of an entirely new technology comes with many problems at the beginning, but over time it improves. It doesn't just get discarded because of minor failures.
As an example, imagine our recent department history being similar to a sudden change from face-to-face airplane booking to automated online booking operations. Of course there will be some technical issues at the beginning - simply because it's new! But what I see is that the former "face-to-face agents" (who now operate the online booking system) are constantly complaning about every minor speck in the online booking system, where their own service level used to be much better and provided a better experience to customers. Now, there are many features that need to be rolled out over time, but certainly not very soon. This is not my industry, but the example is exactly what happened to my team.
What can I do to regain the respect and trust of my team after such a dramatic shift in management strategies?