The word used to mark potential grammatical errors is "sic."
"Sic" is a Latin term that means "thus" or "so." It is used within brackets to indicate that an error or unusual feature in a quotation has been reproduced exactly as it appeared in the original source.
For example, if a sentence in a quotation contains a misspelled word, the word can be marked with "[sic]" to show that the error was present in the original text.
Here's an example:
Original sentence: "She is the bestest [sic] student in the class."
In this example, the word "bestest" is marked with "[sic]" to show that it is not a correct word and was used as it appeared in the original source.
The purpose of using "sic" is to alert readers to the fact that the error is not a mistake made by the person quoting the text, but rather an error present in the original source. It helps to maintain the integrity of the quotation while acknowledging the mistake