I'm using Debian 12, and after installed Calibre and dozens of python dependencies, I started to have the Cairo bug mentioned in (#592).

I made all the troubleshooting with the challenging "Externally Managed Environment Error when using Pip" with no success.

For what I understood, the library Matplotlib cannot see Cairo and displays the error "Gtk-based backends require cairo", which appears to be fixed in version 3.9.1 (matplotlib/matplotlib#28451), but my system has the version 3.6.3.

After installing python3-gi-cairo solves the problem offering Python 3 Cairo bindings for the GObject library.

Thank you