I have a timestring 1661731200 that works as expected when I parse it with Carbon via artisan tinker or in my code using
$time = "1661731200";
Carbon::parse($time);
But the same line of code fails with error Failed to parse time string (1661731200) at position 8 (0): Unexpected character when encountered on the live server.
I'm looking to understand what might be causing this behaviour.

Add the
@timestamp prefix:Or it can be: