Here is a different perspective:
Miranda is a literary agent. She reads your query letter, and she thinks you are describing a book with an interesting premise, and she could probably sell it. Agents work within professional networks, and she has ideas of specific people working for publishers that would like that kind of book.
So Miranda asks for samples, or even for your book to read.
But then, after she has read enough of it, she feels like it starts poorly, or too slowly, or seems off on a tangent. Perhaps it is boring her, there is too much exposition, too much stuff to memorize. For whatever reason, your book is not living up to your query letter, and she can't sell it.
But she has invested some time in reading your stuff, and she thinks it is salvageable, so instead of just throwing it away, she invests another hour in you, by telling you what she expects, and what she (as a professional) thinks is wrong with your book. And if you fix those things, she would give you another read.
Basically Miranda is telling you that your query letter does not match your book, or your book as written will not get published. So if you want to sell, here are some ways you could change what you have done to turn this book into something she could sell.
You can ignore her, but other agents are likely to feel the same. If you are so much in love with your writing that you cannot bring yourself to overhaul it, then your best bet is self-publishing.
Or you can interpret her advice. Understand that your query letter worked but your book did not, it bored her. So see if there is a way to fix the book and reconcile whatever issues were mentioned, perhaps with drastic changes to your text but without any drastic changes to your characters or plot.
For example, there is nothing sacrosanct about your opening; I've never read a story that could not open at an earlier time, and I've read MANY stories that could have opened at a later time. Openings are key and too often filled with boring expository crap (boring because we don't care anything at all about the characters involved, or there are NO characters involved, or there is nothing really happening to engage the imagination of the reader and keep them reading to see what happens).
There is a difference between Miranda effectively telling you to deliver the product you promised in your query letter, and telling you to write something completely different. Yes, she is telling you to write "what she wants", but what she wants is what you promised, and in her view that is not what you sent.
I would add also, it is true she may expect a certain formula, but that is not out of rote. Miranda isn't a machine, she is a thinking person with experience in what works in fiction, and sells. The working "formulas" are not something devised up front and then for no good reason everybody agreed to abide by them. No, they were derived by analysis of centuries of works that had grown very popular, and when publishing became a real thing, stories that sold blockbusters. Studying great stories to see what they have in common has led us to certain formulas to emulate them, and perhaps increase our chances of success. The Three Act Structure, The Hero's Journey, various categorizations of plots (3 or 7 or 21 or 35, depending on how much detail is considered by the categorizations).
So Miranda knows both how stories work and the difference between good prose and bad; and so do the publishers. If she gives you advice to follow a formula, it is because she thinks your work doesn't follow a structure she knows can sell, and that a publisher would accept. So again she is trying to help, for free, by giving you a structure that is currently selling.
We should not be offended by such efforts. At worst, it is like a sincere friend giving you unhelpful advice. But it is worth keeping in mind that if you are not feeling well, and your friend is actually a practicing doctor, perhaps your friend knows something you don't.
If you are rejected or given a list of suggested changes and invited to resubmit, then I'd at least take them seriously enough to realize perhaps something DOES need to be fixed, realize that rejection is a symptom of an underlying weakness in how you are presenting your story.
EDIT, in response to OP comment.
OP: I just don't want the publisher saying they won't publish book A, but if I write the book they've thought of, then they'll publish that. I want to write the books. I do not want to write someone else's book.
It makes no sense for a publisher to do that. If they don't think they can sell the book you DID write, why would they think you would do a good job on their book idea? If anybody did that, they are an egotistical outlier, you can reject them with confidence that you will find nearly all agents and publishers are driven by sales, sales, sales, not ego, they are not there to get their own books written by authors they don't even think they can sell.
I suspect if anybody told you that, what they meant was the publisher wants you to write books for their market in the style they already know sells. If you submit to a Romance publisher and he comes back and says "I like your writing, but you need to do X, Y and Z to turn this into a Romance," then you just made a mistake; your book is not a Romance and you shouldn't be trying to sell it as one. Drop that idea, sell your book as something else.
Agents and Publishers are in it for the money. They DO have niches of particular kinds of stories they like; some more "templated" than others, just ignore those that want to shoehorn you into their genre expectations. If they reject you, it is because they don't think your writing can make them money in their particular genre, their customer base won't buy it. That rejection doesn't necessarily mean you are a bad writer, it could mean you need to find a publisher with a different customer base. This is true even within a niche. JK Rowling was rejected by a dozen YA publishers before one liked the first Harry Potter book. One even told her she should take some writing classes.