This is the output of fc-cache -rv, if it's of any use.
/gnu/store/ag8ilfwcnxn0xnw8bar9ia73h3hg3rra-gs-fonts-8.11/share/fonts: 
caching, new cache contents: 0 fonts, 1 dirs
/gnu/store/ag8ilfwcnxn0xnw8bar9ia73h3hg3rra-gs-fonts-8.11/share/fonts/type1: 
caching, new cache contents: 0 fonts, 1 dirs
/gnu/store/ag8ilfwcnxn0xnw8bar9ia73h3hg3rra-gs-fonts-8.11/share/fonts/type1/ghostscript: 
caching, new cache contents: 35 fonts, 0 dirs
/home/pablo/.guix-profile/share/fonts: caching, new cache 
contents: 0 fonts, 2 dirs
/home/pablo/.guix-profile/share/fonts/truetype: caching, new cache 
contents: 22 fonts, 0 dirs
/home/pablo/.guix-profile/share/fonts/type1: caching, new cache 
contents: 0 fonts, 1 dirs
/home/pablo/.guix-profile/share/fonts/type1/ghostscript: caching, 
new cache contents: 35 fonts, 0 dirs
/run/current-system/profile/share/fonts: skipping, no such 
directory
/home/pablo/.local/share/fonts: caching, new cache contents: 6 
fonts, 0 dirs
/home/pablo/.fonts: skipping, no such directory
/gnu/store/ag8ilfwcnxn0xnw8bar9ia73h3hg3rra-gs-fonts-8.11/share/fonts/type1: 
skipping, looped directory detected
/home/pablo/.guix-profile/share/fonts/opentype: skipping, no such 
directory
/home/pablo/.guix-profile/share/fonts/truetype: skipping, looped 
directory detected
/home/pablo/.guix-profile/share/fonts/type1: skipping, looped 
directory detected
/home/pablo/.guix-profile/share/fonts/webfonts: skipping, no such 
directory
/gnu/store/ag8ilfwcnxn0xnw8bar9ia73h3hg3rra-gs-fonts-8.11/share/fonts/type1/ghostscript: 
skipping, looped directory detected
/home/pablo/.guix-profile/share/fonts/type1/ghostscript: skipping, 
looped directory detected
/var/cache/fontconfig: not cleaning unwritable cache directory
/home/pablo/.cache/fontconfig: cleaning cache directory
/home/pablo/.fontconfig: not cleaning non-existent cache directory
fc-cache: succeeded

But Icecat is still the same after running fc-cache.