Question

Hello, Rabbi,
I wanted to ask what the Rabbi's opinion is regarding marriage between a kohen and a female convert in our time. According to the Torah, the prohibition is specifically regarding a "zonah," and the Sages established that "a zonah is none other than a female convert," in addition, of course, to the usual halakhic definition of someone who had sexual relations with a person whom she was forbidden to marry.
1. What is your view about the very presumption of "a zonah is none other than a female convert" nowadays? Is it appropriate to accept it in every case (even when the past can be clarified)? Is the practical situation in which the Rabbinate forbids marriage between a kohen and a female convert (because of zonah), but permits marriage between a kohen and a Jewess by birth (without checking whether she committed a prohibition that would define her as a zonah), a halakhically necessary conclusion?
2. On a more theoretical level—how can one reconcile the definition "a zonah is none other than a female convert" with "a convert who converted is like a newborn baby"? It does not seem that this is a defect (like a mamzer), but rather a kind of spiritual stain created by the person's own transgression.

Thank you in advance