There are lots of wrong answers out there perhaps for much older versions of LibreOffice.
Tools -> Options
Then under LibreOffice ->Application Colors below.
Change the Viisted and Univisted link colors
Now you should h........
Usually LIbreoffice gets it right, but if it opens a normal English CSV as UTF-16 by default and shows Asian languages, you'll have ot manually open to fix it (don't double click the file from the File Manager).
Solution - Manually Open the File After Opening LibreOffice Calc
You'll see it is defaulting to UTF-16 which breaks everything.
........