In the case of "grifo nosso", "o grifo é nosso" and the like, it's common to use, at least in American English, "emphasis added" in general or "my emphasis" / "our emphasis" depending on who the authors are. By analogy, I suggest using the same principle. See explanation below.

comment added: https://www.google.com/search?q="comment added"

If you add italics for emphasis, indicate that you’ve altered the quotation by using the phrase emphasis added (or my emphasis), like this:

Lincoln specifically advocated a government “for the people” (emphasis added).

https://style.mla.org/cite-altered-quotation/

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Note added at 31 mins (2023-12-14 14:33:53 GMT)
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In-text citations:

The section that is in bold is our comment. Here, we tell the reader what the quote means and explain how it relates to the main idea of our paragraph. https://foxtara.weebly.com/in-text-citations.html