Describe the bug
I can confirm this is issue still exists in Phalcon 5.x - see this: #16979
I have same problem.

To Reproduce

$image = new \Phalcon\Image\Adapter\GD('image-with-transparent-background.png'); //image with a transparent background
$image->resize(500,500); //any new size
$image->save(); //after saving the image has a black background

Expected behavior
Well... to keep PNG transparency or way to maintain that.

Details

• Phalcon version: 5.2.1
• PHP Version: 8.1
• Operating System: Windows
• Server: Apache

Thank you!!!!