Seam (an original image border) visible when using Fill pro Outpainting with official API

[OlegShklyarov]

I Am trying to outpaint an image. Every images I tried has borders. I tried lower guidance, steps - nothing helps. How to avoid borders?

My code is simple:

$postFields = [
    'prompt' => $prompt,
    'steps' => 20,
    'guidance' => 70,
    'safety_tolerance' => 6,
    'output_format' => 'jpeg',
	'image' => $source,
];

I send one image with an alpha mask. But tried also with 2 separate images.