In GuixSD:

guix package -i xterm strace
strace xterm

xterm starts as it should,  however observe many failed calls similar to:
 open("/gnu/store/b484nvn9nnr3ddclpz2fma9yxmimg2jj-fontconfig-2.11.94/lib/libXdmcp.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)


Now in the xterm, hold down Ctrl and press any mouse button.
The xterm aborts with the following messages:
 Warning: Unable to load any usable ISO8859 font
 Error: Aborting: no font found



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