CSV opened in Excel is showing   instead of a space between the DateTime and the period (am / pm)

That is because it is being opened in Excel using CP-1252 instead of UTF-8 and thus rendering the NARROW NO-BREAK SPACE incorrectly
https://www.fileformat.info/info/unicode/char/202f/index.htm
In Excel using Get Data => From Text/CSV and then choosing a file origin of CP-1252 Western European (Windows) you can see it renders it as  

How to open a CSV file with the correct encoding so 'NARROW NO-BREAK SPACE' is displayed correctly
In Excel using Get Data => From Text/CSV and then choosing a file origin of CP-65001 Unicode (UTF-8)

Using PHP to peak into the 'NARROW NO-BREAK SPACE' between the `11:45' and `am'
1 2 3 4 5 6 7 8 9 10 11 | <?php $str = "12/5/22, 11:45?am" ; var_dump(mb_substr( $str ,14,1)); var_dump(mb_ord(mb_substr( $str ,14,1), 'UTF-8' )); # output string(3) "?" int(8239) |
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