I have a test Calc sheet with a date in column A (2019-10-18) and a text field (Test field - with hyphen) in column B containing a hyphen. When I export it as a CSV file, the hyphen in the text field (but not in the date) is replaced by a b, nul, and a dc3. All three hyphens were entered with the normal hyphen key, but the one in the text field looks different. europa 2004 ~ $ od -a Test.csv 0000000 2 0 1 9 - 1 0 - 1 8 , T e s t sp 0000020 f i e l d sp b nul dc3 sp w i t h sp h 0000040 y p h e n nl 0000046 europa 2005 ~ europa 2006 ~ $ cat Test.csv 2019-10-18,Test field – with hyphen europa 2007 ~ $
That is not a U+002D HYPHEN-MINUS but a U+2013 EN DASH instead, exported to UTF-8 text encoding. Not a bug. You maybe had some auto-correction replacement active when entering the data. Using od -a option is a bad choice as it ignores the high-order bit. Better would be od -t x1c Test.csv where you would see that the actual bytes written are 0xe2 0x80 0x93, the UTF-8 encoded EN DASH.