All the VMs in the cluster were live migrated, and on the destination host(s) the network interfaces showed as down inside the guestOS.  
From the logs we see that the network interfaces failed to connect:
~~~
[2:06 PM] 2025-09-12T19:13:30.412984469Z {"component":"virt-launcher","level":"error","msg":"cannot limit locked memory of process 72 to 550829555712: Operation not permitted","pos":"virProcessSetMaxMemLock:917","subcomponent":"libvirt","thread":"26","timestamp":"2025-09-12T19:13:30.412000Z"}
[2:07 PM] 2025-09-12T19:13:30.436491937Z {"component":"virt-launcher","kind":"","level":"error","msg":"failed to hot-plug host-devices: failed to attach host-device <hostdev type=\"pci\" managed=\"no\"><source><address type=\"pci\" domain=\"0x0000\" bus=\"0x26\" slot=\"0x11\" function=\"0x1\"></address></source><alias name=\"ua-sriov-nic-oym-vlan242-ens2f1\"></alias></hostdev>, err: virError(Code=38, Domain=0, Message='cannot limit locked memory of process 72 to 550829555712: Operation not permitted')\nfailed to attach host-device <hostdev type=\"pci\" managed=\"no\"><source><address type=\"pci\" domain=\"0x0000\" bus=\"0xb4\" slot=\"0x13\" function=\"0x6\"></address></source><alias name=\"ua-sriov-nic-oym-vlan242-ens3f1\"></alias></hostdev>, err: virError(Code=38, Domain=0, Message='cannot limit locked memory of process 72 to 550829555712: Operation not permitted')\nfailed to attach host-device <hostdev type=\"pci\" managed=\"no\"><source><address type=\"pci\" domain=\"0x0000\" bus=\"0x26\" slot=\"0x12\" function=\"0x2\"></address></source><alias name=\"ua-sriov-nic-private-vlan253-ens2f1\"></alias></hostdev>, err: virError(Code=38, Domain=0, Message='cannot limit locked memory of process 72 to 550829555712: Operation not permitted')\nfailed to attach host-device <hostdev type=\"pci\" managed=\"no\"><source><address type=\"pci\" domain=\"0x0000\" bus=\"0xb4\" slot=\"0x11\" function=\"0x1\"></address></source><alias name=\"ua-sriov-nic-private-vlan253-ens3f1\"></alias></hostdev>, err: virError(Code=38, Domain=0, Message='cannot limit locked memory of process 72 to 550829555712: Operation not permitted')\nfailed to attach host-device <hostdev type=\"pci\" managed=\"no\"><source><address type=\"pci\" domain=\"0x0000\" bus=\"0x26\" slot=\"0x13\" function=\"0x5\"></address></source><alias name=\"ua-sriov-nic-services-vlan243-ens2f1\"></alias></hostdev>, err: virError(Code=38, Domain=0, Message='cannot limit locked memory of process 72 to 550829555712: Operation not permitted')\nfailed to attach host-device <hostdev type=\"pci\" managed=\"no\"><source><address type=\"pci\" domain=\"0x0000\" bus=\"0xb4\" slot=\"0x12\" function=\"0x4\"></address></source><alias name=\"ua-sriov-nic-services-vlan243-ens3f1\"></alias></hostdev>, err: virError(Code=38, Domain=0, Message='cannot limit locked memory of process 72 to 550829555712: Operation not permitted')\n","name":"quibesdp1","namespace":"altamira-bels-app","pos":"manager.go:569","timestamp":"2025-09-12T19:13:30.436357Z","uid":"392c0a19-193a-4d3e-b496-37866b6d269d"}
~~~

upgraded from 4.19.3 to 4.19.6

Only 1 time, not able to reproduce 

1.
2.
3.

In this case there are 4 VMs on different nodes, each were trigged for a workload migration.  After the migration from within the guestOS all network interfaces showed as down.  
In the virt-launcher logs we could see that the interfaces failed to connect

network interfaces to stay connected