Ok, so that one is quorate and separations seems to have worked there, but they both have the same cluster name, that's not so ideal.
Now, I'd remove the remaining cluster config on the semi-broken node
Bash:
systemctl stop pve-cluster corosync
# start pmxcfs temporary in local mode to make it ignore the cluster config
pmxcfs -l
# remove cluster configs
rm -f /etc/pve/corosync.conf /etc/corosync/corosync.conf /etc/corosync/authkey
# stop local mode pmxcfs again
killall pmxcfs
# start it normally and cleanly via its service
systemctl start pve-cluster
With that it should work again, and the node is not in a broken cluster anymore, albeit there may still be some left-over configurations from the other node from the time they were in a cluster.