Airtable API Date ISO format

Has anyone experienced Airtable doing strange things with dates… it appears there is an invisible conversion happening…

I have a string ‘2019-12-13T15:00:00.000Z’

I pass it via airtable API check this out

to a date field with time… = “12/13/2019 . 9:00 AM” ( Include timefield is on… GMT is off )
to a string field next to it… = ‘2019-12-13T15:00:00’
When I copy the string field to a new table and change the type to date I get the correct date and time… the only issue is when sending a valid string to a datetime column it adds some sort of offset… See screenshot

The Calendly Start Event time is wrong… All 3 columns are fed the exact same datetime string to the airtable API