id usermod useradd escaping root and reading /etc/passwd etc of host

[mangodan2003]

I'm not sure where the fault is here, but since Ubuntu 22.04 (previous known working was 20.04) id, usermod etc escape fakeroot filesystem and read hosts files as shown by:

dan@melon:~$ fakechroot fakeroot -i tmp/fakeroot.save -s tmp/fakeroot.save chroot tmp/root/ /bin/bash
root@melon:/# grep  'messagebus\|dan' /etc/group
messagebus:x:102:
root@melon:/# usermod -G  messagebus messagebus
usermod: group 'messagebus' does not exist
root@melon:/# usermod -G dan dan
root@melon:/# exit
exit
dan@melon:~$ grep  'messagebus\|dan' /etc/group
dan:x:1000:

Specifying a relative prefix for usermod makes it work, but doesnt realy help as the problem I'm facing originate in postinst files whilst running apt:

root@melon:/# usermod -G  messagebus messagebus
usermod: group 'messagebus' does not exist
root@melon:/# usermod -G  messagebus messagebus -P ../../
root@melon:/# usermod -G  messagebus messagebus -P /     
usermod: group 'messagebus' does not exist

Why is it that grep sees /etc/passwd of the fakeroot filetree, yet id sees that of the host? They seem to both be linked against the same fakechroot and libc libraries, but i do notice id is linked with sellinux.

root@melon:/# /bin/grep dan /etc/passwd
root@melon:/# id -u dan
1000
root@melon:/# ldd /bin/grep
        linux-vdso.so.1 (0x0000000000000000)
        libfakeroot-sysv.so => /usr/lib/x86_64-linux-gnu/libfakeroot/libfakeroot-sysv.so (0x0000000000000000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x0000000000000000)
        /lib64/ld-linux-x86-64.so.2 (0x0000000000000000)
        libfakechroot.so => /usr/lib/x86_64-linux-gnu/fakechroot/libfakechroot.so (0x0000000000000000)
        libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x0000000000000000)
root@melon:/# ldd /usr/bin/id 
        linux-vdso.so.1 (0x0000000000000000)
        libfakeroot-sysv.so => /usr/lib/x86_64-linux-gnu/libfakeroot/libfakeroot-sysv.so (0x0000000000000000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x0000000000000000)
        /lib64/ld-linux-x86-64.so.2 (0x0000000000000000)
        libfakechroot.so => /usr/lib/x86_64-linux-gnu/fakechroot/libfakechroot.so (0x0000000000000000)
        libselinux.so.1 => /lib/x86_64-linux-gnu/libselinux.so.1 (0x0000000000000000)
        libpcre2-8.so.0 => /usr/lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x0000000000000000)