Note that in the file client/write/point.py the ciso8601 library is used to convert
timestamp strings to datetime.datetime objects,

However, the datetime.datetime format returned no longer supports nano-seconds, it ignores everything past microseconds

In [181]: ciso8601.parse_datetime('1996-02-25T21:20:00.001001231Z')
Out[181]: datetime.datetime(1996, 2, 25, 21, 20, 0, 1001, tzinfo=datetime.timezone.utc)

Since nano-seconds are the default write precision for the DataBase, this is a major failure

No simple solution here -- the datetime libraries use dto support nanosecs, but in a streak of purism were changed to be POSIX compliant (and posix only talked about microseconds).