'now' is a relative time notation. However, the response doesn't contain a 'relative' section as we see with date_parse('+0 seconds')

Expected result:
----------------

[
  "year" => false,
  "month" => false,
  "day" => false,
  "hour" => false,
  "minute" => false,
  "second" => false,
  "fraction" => false,
  "warning_count" => 0,
  "warnings" => [],
  "error_count" => 0,
  "errors" => [],
  "is_localtime" => false,
  "relative" => [
    "year" => 0,
    "month" => 0,
    "day" => 0,
    "hour" => 0,
    "minute" => 0,
    "second" => 0
  ]
]

You can deduct that 'now' was parsed as it's the only value that gives this specific result, however that's merely a workaround.

The documentation[1] states:

| 'now'   Now - this is simply ignored

So this is expected behavior.

[1] <https://www.php.net/manual/en/datetime.formats.relative.php>