As seen here: https://github.com/elastic/elasticsearch/pull/46473/files#diff-cf94de789c0241585ea4400a0761e0f9R125 the .XXX milliseconds part of the expected timestamp is ignored and currently the work around is to cast the timestamp result columns as string in order to properly assert them.
The issue should be fixed either through CsvTestUtils or maybe by patching the 3rd party csvjdbc library .