So, the root cause of the issue is that, for some reason, haproxy is not restarted with new set of 'other_networks' parameter which controls the networks that should be routed through the host out of haproxy namespace and thus the packets do not reach newly added compute nodes from the new node group.
So, the root cause of the issue is that, for some reason, haproxy is not restarted with new set of 'other_networks' parameter which controls the networks that should be routed through the host out of haproxy namespace and thus the packets do not reach newly added compute nodes from the new node group.