Why does Libre Office Calc, when importing an xlsx sheet into csv, use backslash instead of double quotes to escape values?

Question

linux

I'm trying to export the active sheet of an xlsx file to a csv file via the "save as" function. In the resulting text file, only some of the values ​​in the first column are escaped with double quotes. Most values ​​that contain commas are enclosed in backslashes.

Where could this syntax come from and how can I turn it off? The creation of the xlsx file and the import attempt were made in Libre Office Calc 6th version from Linux Mint OS. Libre Office after the discovery of the problem was updated to the 7th, but this did not solve the problem. Manipulating the csv setting flags didn't help either. Below is an example of the result.

column_one,column_two
тест проверка продолжаем тестирование,\раз,два,три,четыре,пять\
\ну тут будет ещё один тест,второй\,ещё значение

Answer 1

I checked, by default it exports with quotes (ver.6.4.6.2):
​​"apukgf, rukf", k740 pl, "89, pr"
when exporting, you can specify any character instead of quotes