Hello,
Thank you for the answer.
But I still didn’t understand—if the taste inside the utensil is considered spoiled, why does it need koshering by boiling?
Thank you

I answered. It’s the difference between ideally and after the fact. Ideally one should not use the utensil, but after the fact it does not prohibit the food. Some prohibit it even after the fact if one intentionally used that utensil.

Hello,
Thank you for the answer, and sorry for being so persistent with the questions, but again I didn’t understand—
If after 24 hours all the utensil emits is spoiled taste and it causes no problem at all in the food into which it is emitted, why is it forbidden to use, for example, utensils in which a gentile cooked non-kosher food (after waiting 24 hours), or for a Jew to use a meat utensil, wait 24 hours, and then use it for dairy, and so on?
Thank you

I don’t know what else I can say besides repeating my answer for the third time. There is a difference between ideally and after the fact. That is true in many areas of Jewish law, and here too. The utensil is forbidden, but after the fact it does not prohibit the food (unless one used it intentionally). Just as one does not convert a convert for the sake of marriage, but if they did convert him, the conversion takes effect.
That’s it—if some other point in the question does not become sharper, I won’t answer further.

I think he means the reason for the decree, and the answer is that it is written in tractate Avodah Zarah that by Torah law only utensils used within the same day are forbidden (in the passage about the utensils of Midian), and the Sages came and decreed also regarding utensils that are not of the same day because of those that are of the same day, and therefore ideally they must be koshered by boiling.

Your question can be asked more generally about any case where something is forbidden ideally but permitted after the fact. Usually, in my humble opinion, the logic is that if they had permitted it even ideally, people would often end up reaching an actual prohibition, so they permitted it only after the fact. For example here, if they had permitted using the utensil ideally after a day, people would end up being lenient in the law and using utensils that are non-kosher even without waiting 24 hours. However, since the matter is not intrinsically forbidden, and they are protective of your property, they permitted it after the fact.

With a sharp food there is a problem eating it even when the utensil gives spoiled taste, and because of that use as well, even though it is a minority case, the utensil must be koshered by boiling.

Best regards, Yiftach Lahad Argamon-Bakshi