This is a good fix for handling JSON values. However, the current implementation has a few issues that should be addressed:

1. PHP Compatibility (critical): The use of str_starts_with() was introduced in PHP 8.0. Using it will break backward compatibility for projects running on older PHP versions, which this library appears to support.
2. Redundant Parsing (high): The code uses preg_replace('/^.*?:\s*/', '', $line) to re-extract the value from the line. This is unnecessary and less efficient, as the value has already been correctly parsed into the $value variable.
3. Brittle JSON Detection (medium): The condition to detect a JSON string is too specific. It will fail for valid JSON with leading whitespace (e.g., { "key": "value" }) or other valid JSON structures.

I've provided a suggestion below that resolves all these points by using a more robust and backward-compatible approach.

        // The default inline parser (_toType) does not correctly handle complex JSON objects.
        // Attempt to parse as JSON first for values that look like potential JSON.
        $first_char = isset($value[0]) ? $value[0] : '';
        if ($first_char === '{' || $first_char === '[') {
          $decoded = json_decode($value, true);
          // If the value is valid JSON, use the decoded array.
          // This correctly handles valid JSON 'null' as well.
          if (json_last_error() === JSON_ERROR_NONE) {
            $value = $decoded;
          }
          // Otherwise, leave $value as a string for the legacy parser to handle.
        }