The output of grub2-mkconfig ends with:

Found hypervisor: /boot/xen-4.13.0_01-2.gz
Found linux image: /boot/vmlinuz-5.3.8-1-default
Found initrd image: /boot/initrd-5.3.8-1-default
awk: cmd. line:18: warning: regexp escape sequence `\"' is not a known regexp
operator
awk: cmd. line:18: warning: regexp escape sequence `\"' is not a known regexp
operator
cp: -r not specified; omitting directory '/boot/'


It seems to be broken by gawk update to version 5. See
https://github.com/KittyKatt/screenFetch/issues/627 and
https://dev.gnupg.org/T4492 for references.