The reason it lingers is multifaceted, regardless of whether the misgendering was intentional or otherwise. In either case it's a slap in the face from reality that for all the "you look amazing girl"s and "slay queen"s they get when they ask Reddit if they pass, outside of internet hugboxes they simply don't and never will. An especially rude awakening to those who have deluded themselves into thinking that they genuinely pass.
In the case of deliberate misgendering, it is an explicit gesture of refusal to play by their rules, be gaslit into ignoring what their senses perceive and lie to themselves and others. These autistic narcissists hate nothing more than feeling a loss of control over those around them, and being deliberately misgendered is the equivalent of a punch in the face in that regard.
Unintentional misgenderings are, if anything, more hurtful to them. Their being misgendered wasn't informed by malice, prejudice, transphobia or anything else they can blame- rather the misgenderer's brain just automatically printed out the word 'male' upon seeing them and then their mouth acted accordingly. Just an entirely automatic, subconscious and natural process of seeing a thing and then responding to that thing. Nothing to blame and scream at but human nature and reality itself.
Responses to being misgendered are always very telling. I'm a so-called 'cis' man and haven't ever been misgendered, but I can tell you for a fact that if I ever were to be, my reaction would be mild confusion at worst, indifference at best. Trannies don't realise that when they start stamping their feet and "IT'S MA-AM"-ing, they completely debase the legitimacy of their claims of being a woman, (not just because of the male-brained nature of their response but) because they always see it as an attack and not the simple mistake that it probably was. Cis people's 'gender identity' cannot be shaken in this way because it just 'is'. Clear as day. Even if an effeminate man takes umbrage at being called 'girly', he is still fundamentally a man and always will be. It would be like if you called a dog a cat- even if it could understand what you were saying, it wouldn't give a shit because nothing would change in any way whatsoever within the boundaries of objective reality and it would still act according to it's nature.
When you get caught between the troon and Jew York tunnels...