Previously, copying a selection would always use PNG, but now it follows the "Image Saving" file format. A separate option for which format to use for copying to clipboard would allow users to save in a more efficient but less widely supporter format while copying in a widely supporter format.
*** This bug has been marked as a duplicate of bug 447831 ***
Actually, I might have been a bit hasty marking as a duplicate. Do you specifically want a setting just like the existing setting for save formats? Is that just an idea you came up with that fits your needs but not something you specifically need? The bug I marked this as a duplicate of is "Add the ability to Copy to clipboard as a specific image format"
This commenter https://bugs.kde.org/show_bug.cgi?id=447831#c7 shares the same use case as me. A separate setting for copying would be ideal, but the previous behavior of copying as PNG would also work for me.