I’ve also noticed discontinuity in timestamps throughout the API. Some are pre-formatted to human readable time and some are in Unix milliseconds with a timezone offset in milliseconds. I would rather see everything in Unix epoch for uniformity and let me (a developer) structure the datestamp with struct time.
To reformat a timestamp that is zulu time to how I want it formatted requires split, replace, or even a regex. All of that can be avoided if it was in Unix time like the rest of the API.
Thankfully the API includes my timezone preference and correct offset allowing me to join them to create my correct local time. Whoever works on the API, thank you for including the TZ offset, that definitely helps.