What to do as a grad student about an adverse grader? I'm a grad student and one course I'm taking is graded by another grad student. Today, nearly halfway through the term, we finally got feedback on all our previously submitted homework dating back to the beginning of the term. I've done everything correctly, but the grader has frequently marked me down for not including steps in my work which are so obvious I would never, as a grader myself, consider marking sophomores down for passing over them without comment, much less fellow grad students. And on a couple of occasions he's marked me down for reasons which are plainly factually incorrect.

I can see statistics for each assignment's grades and it looks like I may be the only one getting dinged like this; other students are generally getting either perfect scores or scores low enough that it should indicate they've actually gotten things wrong. I begin to wonder whether the grader has it out for me. At the present rate I could end up with a B+ or A- on my transcript for this relatively easy course where I'm turning in practically perfect work.

The fact that I'm only finding this out halfway through the term does make things worse, but even if I'd known beforehand that he'd grade this way, honestly I don't think I could possibly have predicted the particular trivialities he's insisting on. So the only way I can imagine ruling those out is by turning straightforward single-page TeX'd assignments into ten-page exercises in stating the obvious. And then there are the problems where his stated reason is simply wrong.

During the pandemic, courses are being held remotely, and the site we use for submitting homework and viewing feedback includes a way to request a regrade. But it appears that request goes to the grader, and if this is a pattern of unfair treatment I'm not sure about confronting him about it. Yet I don't want to disproportionately hassle the professor, who I've never met before this class but who has commented positively on my comments in class.

How should I address this in a way that doesn't escalate things/burn bridges/whatever but does address the problem?

Edit: a couple people are misunderstanding. This isn't about me looking for 'leniency' on 'harsh grading.' I've done the work correctly, and the grader has taken exception to my style or something; he apparently hasn't been dinging other students similarly. I didn't intend to adduce examples, but perhaps given the misunderstandings it's necessary, so here are two. I showed a particular vector space was n-dimensional and exhibited n linearly independent vectors, and concluded they were a basis; I was marked down for not explaining why. I wouldn't expect sophomore linear algebra students to tediously reiterate every single time that any set of n linearly independent vectors in an n-dimensional space form a basis, much less grad students. In another instance I was marked down for saying the singular value matrix is diagonal, with the grader complaining that it's only diagonal if it's square. That's simply an overly restrictive use of the term; what I said was correct and clear.
Of course, you are perfectly entitled to get graded fairly. Talk to the prof, and when you do, concentrate on the factually wrong grades if they are the substantial part of your complaint, because that's where you can provably address the factual incorrectness of the marking. Make absolutely sure this is really the case; if you get that wrong, people won't listen to you on the other things. 

If the professor looks at that, you could add as an afterthought that you generally feel that the grader is overmeticulous, and whether you are really supposed to submit at that level of detail? 

Generally, much will depend upon how well you do on other courses. 

I would completely put aside the thought whether the grader has it in for you, as you have no way to prove it, unless you have hard evidence for that (e.g. some proof of a conflict of interest or something else). I would avoid going down that route, though.