@richard: This is already reported and fixed:
https://github.com/kovidgoyal/calibr...5f8c819b7b4dc2
@jiembe: You are probably overriding the calibre lt.png/library.png icon in your icon theme. The protections I put in the code to prevent it being overridden dont work with the new icon loading scheme. I will have to update them.
https://github.com/kovidgoyal/calibr...a334954e3c9e36
@theducks: That looks like the eraser icon. Dunno why you are seeing it? You using a custom icon theme?
@BR: The support for changing icon themes dynamically on light/dark switch requires them to be packaged differently. You should be able to override individual icons in the config folder still, but if you have an entire icon theme unzipped there it get auto repackaged.
And the calibre-ebook.com folder is likely created by Qt for some of its settings, remind me in the future to look into how to prevent it doing that.