The following CSV contains "9-2" and other similar strings. In Chrome, this gets parsed by SheetJS as 37136, which I believe to be an Excel date representing 09-02-2001. In Firefox and other browsers, it remains "9-2".
Serial numbers: https://support.microsoft.com/en-gb/office/date-systems-in-excel-e7fe7167-48a9-4b96-bb53-5612a800b487
Convert from serial number to date: https://serialnumbertodate.com/