I suffered with this problem quite often with my previous job. There would be something vague assigned to me and I didn't quite get what to do but I also felt like if I asked questions, it'd give off a vibe like I didn't know what I was doing so I would just start programming and making a bunch of assumptions.
That wasted a lot of time which is a lesson to be learned from.
I also struggled with self management.
I struggle with this a lot. I'm currently about ten years in to the career and technically at my org I'm a "senior".
One issue I have quite often is I'll know I have a problem with understanding something and so I ask my team but then the response can be something like "you should know X" or "you should know this because of Y context" and it can be discouraging. I think a lot of the time I notice people conflate experience level with amount of context I have with something.
I'm still struggling with these kinds of challenges and I would readily admit it could be my own weakness but I also wonder if it's a team culture issue; but I've noticed this across my current org and my last one so maybe it's more of a me-problem.
usually what i did is to take an abstract spec, derive thick layers / modules to decompose the problem, and then look at the deadline to see what MVP i can draw in that space.
whenever that mvp is not what was expected, if i'm lucky enough, the decomposition allows for easy adjustements to match the need
This is very common behavior. This is where a good manager can really help. They can recognize this is happening and then provide context.
One approach to deal with ambiguity is to write a short design doc, which writes down what you are trying to do, and all of the assumptions that you are making. If you don't understand the domain, some of your assumptions will probably be wrong. The stakeholder should be able to see that and provide guidance.
My superpower as a staff engineer was having zero shame in asking questions. Anything from "what does that abbreviation stand for?" through to "what will the traffic look like when we go live?" - mostly people are worried about looking ignorant, so weirdly this makes you look both knowledgeable and confident! I wish I'd known that when I was younger...