Problem/Motivation
According to php documentation when converting image to webp quality argument can be passed to set the quality of the image.
In gd.php default is set to 80% and there is no way to configure or change this value.function imagewebp($image, $to = null, $quality = 80): bool {}
Steps to reproduce
Go to admin/config/media/image-toolkit
Select GD2 for image processing
Only JPEG quality is configurable not WEBP.
Proposed resolution
Make the quality settings configurable and pass the configured value to imagewebp().
User interface changes
When selected GD2 to process images add an additional field to take the WEBP quality value similar to ones taking JPEG.