Here is a thing: Not every hyper-competent female character is a Mary Sue.
Not even if the hyper-competent female character is also physically attractive.
Not even if the hyper-competent and physically attractive female character is in a book written by a female author.
Not even if the hyper-competent and physically attractive female character is in a book written in first person pov by a female author.
In news that may come as a shock to some of you, writers are human beings. We make mistakes. Sometimes those mistakes are in our writing, and sometimes those mistakes we make in our writing involve our characters. We love them, and so we tell you - the reader - about how they made the honor roll and got the lead in the school play, and not about the time they snuck out, got drunk, and came home coated in vomit and sporting an embarrassing tattoo. When that happens, that's a failure of characterization on the part of the writer.
But sometimes, the character is hyper-competent. Characterization can fail here, too - a woman who has never before seen a sword or been in a military environment who picks up a broadsword or rapier and is the best knight in the land? Completely unbelievable. But this is equally unbelievable when the character who does this is a man. Even if his name is Galahad. A someone who trained - and seriously - with a sword for many years, I can assure you that gender is no inherent guarantee of skill. Unearned competence is writerly failure - earned competence, even in the extreme, is not.
Let me repeat - earned competence is not a sign of a Mary Sue, even if that competence causes someone to be the best person in the story (or in the world of the story) at Thing X. Even if she's a cute competent woman, with a cute girl- or boyfriend, who is also competent and desirable in the world of the story. (Is there a problem if everyone, including vowed celibates, eunuchs, people in committed relationships, and people of noncompatible sexual orientations spend the entire book trying to tap that? Probably.)
Why am I wearing my rant pants on this? Well, partially because as a red-headed woman with central heterochromia and skill with a sword I am an actual person who can check off a fair amount of boxes on the Mary Sue test. And yes, I'm mildly annoyed about this. I am a character, dammit, not just a collection of characteristics. (Rant for another day: a character who is a survivor of sexual violence or abuse gets a tick box on the Mary Sue check list? What the fuck is wrong with people?)
But mainly, it's because I see this idea more and more - particularly in relation to point of view characters in urban fantasy, but not solely there (I can't be the only one who has seen references to Hermione as being Rowling's Mary Sue, can I? And no, she's not: earned competence, people. Hermione studies her ass off.), the idea that any time a woman writer writes a woman character who is really good at something, who is the hero of her own story, that character gets dismissed as being simply a Mary Sue. It's as if the idea that there might be competent women out there is harder to believe in than dragons or AI.
A writer can fail in characterization in a lot of ways. But writing a smart woman, who's really good at what she does? That's not failure. That's something to aspire to.