See from log:

sudo[29649]: PAM unable to resolve symbol: pam_sm_setcred
sudo[29649]:   werner : TTY=pts/2 ; PWD=/suse/werner ; USER=root ; COMMAND=/bin/bash
sudo[29649]: pam_kwallet5(sudo-i:setcred): (null): pam_sm_setcred
sudo[29649]: pam_systemd(sudo-i:session): pam-systemd initializing
sudo[29649]: pam_systemd(sudo-i:session): Asking logind to create session: uid=0 pid=29649 service=sudo-i type=tty class=user desktop= seat= vtnr=0 tty=pts/2 display= re>
sudo[29649]: pam_systemd(sudo-i:session): Session limits: memory_max=n/a tasks_max=n/a cpu_weight=n/a io_weight=n/a runtime_max_sec=n/a
sudo[29649]: pam_systemd(sudo-i:session): Not creating session: Already running in a session or user slice
sudo[29649]: pam_unix(sudo-i:session): session opened for user root(uid=0) by werner(uid=0)
sudo[29649]: The gnome keyring socket is not owned with the same credentials as the user login: /run/user/223/keyring/control
sudo[29649]: gkr-pam: couldn't unlock the login keyring.
sudo[29649]: pam_kwallet5(sudo-i:session): (null): pam_sm_open_session
sudo[29649]: pam_kwallet5(sudo-i:session): pam_kwallet5: open_session called without kwallet5_key
sudo[29649]: pam_xauth(sudo-i:session): requesting user 0/0, target user 0/0
sudo[29649]: pam_xauth(sudo-i:session): current and target user are the same, forward X11
sudo[29649]: pam_xauth(sudo-i:session): reading keys from `/root/.Xauthority'
sudo[29649]: pam_xauth(sudo-i:session): running "/usr/bin/xauth -f /root/.Xauthority nlist :3" as 0/0
noether sudo[29649]: pam_xauth(sudo-i:session): no key

... that mean that requestinf user as well as target
user is root ... now compare this with su(8):

su[29813]: The gnome keyring socket is not owned with the same credentials as the user login: /run/user/223/keyring/control
su[29813]: gkr-pam: couldn't unlock the login keyring.
su[29813]: pam_kwallet5(su:auth): (null): pam_sm_authenticate
su[29813]: (to root) werner on pts/2
su[29813]: pam_kwallet5(su:setcred): pam_kwallet5: pam_sm_setcred
su[29813]: pam_systemd(su:session): pam-systemd initializing
su[29813]: pam_systemd(su:session): Asking logind to create session: uid=0 pid=29813 service=su type=tty class=user desktop= seat= vtnr=0 tty=pts/2 display= remote=no remote_user=werner remote_host=
su[29813]: pam_systemd(su:session): Session limits: memory_max=n/a tasks_max=n/a cpu_weight=n/a io_weight=n/a runtime_max_sec=n/a
su[29813]: pam_systemd(su:session): Not creating session: Already running in a session or user slice
su[29813]: pam_unix(su:session): session opened for user root(uid=0) by werner(uid=223)
su[29813]: The gnome keyring socket is not owned with the same credentials as the user login: /run/user/223/keyring/control
su[29813]: gkr-pam: couldn't unlock the login keyring.
su[29813]: pam_kwallet5(su:session): pam_kwallet5: pam_sm_open_session
su[29817]: pam_kwallet5: final socket path: /run/user/223/kwallet5.socket
su[29817]: pam_kwallet5-kwalletd: Couldn't listen in socket
su[29813]: pam_kwallet5(su:session): pam_kwallet5: Couldn't fork to execv kwalletd
su[29813]: pam_xauth(su:session): requesting user 223/50, target user 0/0
su[29813]: pam_xauth(su:session): /suse/werner/.xauth/export does not exist, ignoring
su[29813]: pam_xauth(su:session): /root/.xauth/import does not exist, ignoring
su[29813]: pam_xauth(su:session): reading keys from `/suse/werner/.Xauthority'
su[29813]: pam_xauth(su:session): running "/usr/bin/xauth -f /suse/werner/.Xauthority nlist :3" as 223/50
su[29813]: pam_xauth(su:session): writing key `<deleted_key>' to temporary file `/root/.xauthmUclTx'
su[29813]: pam_xauth(su:session): running "/usr/bin/xauth -f /root/.xauthmUclTx nmerge -" as 0/0

here it simply works (the Xsession cookie I've replaced with <deleted_key>)