appstream-generator gives the following error while processing the image:
Could write new image generated from 'spectacle.svgz' (package 'spectacle-21.04.0-1-x86_64.pkg.tar.zst'): XML parse error: error code=200 (3) in (null):5:69: xmlns:graph: Empty XML namespace is not allowed 

I simply opened and saved the unedited file in Inkscape to fix possible bugs.