Same issue, like JDK-8281682, but on Linux.

jpackage unconditionally adds launcher icons in the app image [1].

If --icon or --linux-shortcut options are not specified, jpackage should not add .png files to the app image. They are just dead weight serving no purpose.

[1] https://github.com/openjdk/jdk/blob/e8e2aadd9ea302b7b448d0fda9d069d3813f31c5/src/jdk.jpackage/linux/classes/jdk/jpackage/internal/LinuxPackagingPipeline.java#L68