Port collisions between pod and cluster IPs on OpenShift 4 with OVN-Kubernetes

Issue

• pod-to-pod communication is suddenly broken after a while, even if both source/destination pods are hosted on the same Openshift worker node; if pods are redeployed, they can communicate again for some time before the issue arises again
• The OVS pod are showing failed (Invalid argument) on packet logs:

2021-03-12T08:12:40.670Z|00004|dpif(handler10)|WARN|system@ovs-system: execute ct(commit,zone=84,label=0/0x1),ct(zone=85),recirc(0x19590) failed (Invalid argument) on packet udp,vlan_tci=0x0000,dl_src=0a:58:0a:81:02:07,dl_dst=0a:58:0a:81:02:08,nw_src=10.129.2.7,nw_dst=10.129.2.8,nw_tos=0,nw_ecn=0,nw_ttl=64,tp_src=5054,tp_dst=5088 udp_csum:14c4 with metadata skb_priority(0),skb_mark(0),ct_state(0x21),ct_zone(0x54),ct_tuple4(src=10.129.2.7,dst=10.129.2.8,proto=17,tp_src=5054,tp_dst=5088),in_port(16) mtu 0