There’s no plot hole
The fruit gave knowledge of Good and Evil. There is no suggestion that it gave the requisite wisdom, experience, compassion and fortitude to *use *that knowledge.
In condensed form, pre-fruit humans had a dependent relationship with God. God told them what to do, they obeyed, and God provided for all their needs. Humans had neither the need not the ability to discern moral issues. They simply listened to God, who was always morally right.
Presumably humans at this stage didn’t even have the ability to understand *why *something was morally right or wrong. Like small children, they were told that some things were naughty and shouldn’t be done and they didn’t do those things, and they were told that some things had to be done and they did them. Humans were like children, lacking any real capacity to understand complex moral argument.
Post-fruit humans understood morality. They could utilise moral reasoning and make decisions on what was right or wrong according to their own standards. At that stage they became like humans are right now. But there is no suggestion in the text that gained any other abilities. Just like modern adults, Eve gained knowledge of good and evil. She no longer did things because she was told to to by God, she did them because could decide for herself whether something was right or wrong.
But that was the only ability she gained.
She didn’t magically gain any precognition about the *consequences *of evil actions. She, and her descendants, had to be told that later by God, or find it out by experience.
She didn’t magically gain the ability to reliably choose to do Good over doing Evil. Or to choose between two actions, both of which were both evil.
She was faced with, for example, the choice of growing old and dying alone in the wilderness or tricking Adam into eating so he would be banished with her. She knew which one was an Evil act, but she didn’t magically gain the self-control to condemn herself to save her spouse. Just as many people today would choose to drag their spouse into their shit in order to not die alone, so did Eve. And she presumably did it for the same reasons: she justified it by telling herself that God would forgive them both if she tricked Adam into it. Or she justified it by saying that Adam owed it t her. Or she may have just panicked, and self-preservation and desperation drove her to committing what she knew was an evil act, just as it has for so many other people throughout history.
The point being that we, as humans, can know perfectly well that an action is morally wrong, and still commit that act. Knowing that something is wrong, even perfect knowledge, doesn’t prevent us from undertaking the wrong action through fear or justification. Eve only gained one superpower: an ability to know what was right and what was wrong. She didn’t gain the perfect wisdom and empathy and clairvoyance and self-sacrificing nature that we all know is required for any human to never undertake an act that they know is morally wrong.
Or to put it in simple terms: Eve was exactly like we are today. How many people today commit acts that they know are morally wrong? I know I’ve done it, and I’m sure you have too. And we’ve grown up in a world where we have been faced with this dilemma endlessly, and have the experience and wisdom to both think about it in advance and contextualise it when it presents itself. Eve had never been faced with such a choice in her life, had never had anyone to learn from and had no reference point aside from her own morality.
Hardly surprising she made a bad call when her very first moral dilemma was literally life-or-death: choose good and be condemned to a thousand years of starvation and loneliness before dying childless in the wilderness or choose evil and drag your husband in with you.
How many people today would be unaware which is the moral thing to do when faced with that choice? Yet how many are prepared to drag their spouse into their shit in order to avoid dying alone?
In summary, there’s no contradiction. You are assuming that knowledge of Good and Evil somehow comes with the ability to always choose Good. But that is neither explicit nor implied in the text. We are descendants of Eve, we have all her abilities. And while I certainly have the ability to discern morality, I don’t have any ability to always act morally, especially when doing so will cause my own death.
Now you can say that the author should have expanded more on the reasons *why *Eve chose the Evil option, despite knowing that it was wrong. But that’s not a plot hole. The fact is that we could come up with a thousand plausible reasons why she did it, with real world examples of people doing similar`things.