I tried to use the luxon library to move away from moment - to translate the 1615065599.426264 timestamp into an ISO date.
According to the Online Epoch Converter this corresponds to
GMT: Saturday, March 6, 2021 9:19:59.426 PM
Your time zone: Saturday, March 6, 2021 10:19:59.426 PM GMT+01:00
Relative: 3 days ago
Removing the decimal part gives the same result.
The code using luxon:
let timestamp = 1615065599.426264
console.log(luxon.DateTime.fromMillis(Math.trunc(timestamp)).toISO())
console.log(luxon.DateTime.fromMillis(timestamp).toISO())
<script src="https://moment.github.io/luxon/global/luxon.min.js"></script>
This result is
1970-01-19T17:37:45.599+01:00
1970-01-19T17:37:45.599+01:00
It is suspiciously close to Unix Epoch (1970-01-01 00:00:00).
Where is my mistake?