Unsharp Mask extension is broken

Summary:

Applying Unsharp Mask on bitmap image fails.

Steps to reproduce:

• Start Inkscape.
• Import a bitmap image like png or jpg.
• Apply Unsharp Mask extension on it.

What happened?

The image is not modified at all no matter what values I enter in the extension GUI.

What should have happened?

The image should be sharpened.

Version Info:

Inkscape: 1.0 (4035a4fb49, 2020-05-01)
Operating System: Manjaro Linux 
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.70.0
Qt Version: 5.15.0
Kernel Version: 5.7.0-3-MANJARO
OS Type: 64-bit