Issue PHP GD library misbehaving when using imagecropauto()

[dbitsch]

Hi,

When I use the PHP GD library function imagecropauto() to crop my images (png; transparency) the resulting image differs from my local dev environment. (found here)

Command I use:

$img = imagecreatefrompng($image_path);
$cropped = imagecropauto($img, IMG_CROP_SIDES);
imagepng($cropped, $filename_cropped);

Result on the latest Plesk Onyx Update: (left original; right cropped)

It successfully crops the image, but it keeps on adding abstract looking backgrounds. Sometimes they are even in green, even though the color doesn't appear in the image itself.

For everyone not knowing imagecropauto(): It crops colored/transparent areas of images sides, even one sided crops are possible. In case the above images are not clear, this here is:

On my local dev environment (docker, ddev, php 8.2) everything looked perfect after cropping.
My first thought was up/downgrading the php-gd library, if that's possible, but I suppose on Plesk installations this won't be easy since GD is coming from custom plesk packages if I'm right.

Any idea how I can get it running with Plesk?

- Dennis