Incorrect display of system fonts after guix system reconfigure (2021_10_29)

[Christophe Pisteur]

Hello, 
I installed some time ago guix system (1.3) on a Lenovo libreboot with
the gnome desktop.
I made today:guix pullfollowed by sudo guix system reconfigure
/etc/config.scm
and I lost the cantarell fonts for the gnome desktop display. I then
selected (in gnome-tweaks) the available fonts (liberation serif, etc.)
but the display of the menus is still faulty (bold fonts without
precise outline). The problem already appears from the gdm login
screen.
So I went back to the previous generation and everything is displayed
correctly (with liberation serif as with cantarell).
Below is the list of the two generations of guix system concerned.
Generation 6 is working; generation 7 is the one with the problem. 
Any ideas? 
Christophe
---------------------------------------------------------------------
----
Génération 6    04 oct 2021 16:47:11    (actuelle)  nom de fichier :
/var/guix/profiles/system-6-link  nom de fichier canonique :
/gnu/store/90srxmrcc0a5d826zz0p0f161hnjc11d-system  étiquette : GNU
with Linux-Libre 5.14.9  chargeur de démarrage : grub  périphérique
racine : UUID : ea096464-f368-46b6-a1f8-c9c0e2c9736d  noyau :
/gnu/store/k1xanirwdhy14clvnfc1q5fwm39znxhb-linux-libre-5.14.9/bzImage  
canaux :    guix:      URL du dépôt : 
https://git.savannah.gnu.org/git/guix.git      branche :
master      commit : a03562b478f50c302b6398fe5793fc072ed621f2  fichier
de configuration : /gnu/store/idfmbzq8lvcs0dmq23g89x61fk6zalvq-
configuration.scm

Génération 7    29 oct 2021 08:04:51  nom de fichier :
/var/guix/profiles/system-7-link  nom de fichier canonique :
/gnu/store/a5g97vcml10cjw833cmxvy0p5mplv9gs-system  étiquette : GNU
with Linux-Libre 5.14.15  chargeur de démarrage : grub  périphérique
racine : UUID : ea096464-f368-46b6-a1f8-c9c0e2c9736d  noyau :
/gnu/store/dm0y0agial5vzsni0b398ykdkxwfg1yr-linux-libre-
5.14.15/bzImage  canaux :    guix:      URL du dépôt : 
https://git.savannah.gnu.org/git/guix.git      branche :
master      commit : ad39268cdf075f4c4eeb87ed78ce46ca6f817675  fichier
de configuration : /gnu/store/idfmbzq8lvcs0dmq23g89x61fk6zalvq-
configuration.scm