Kea and virtual network conflict

I have kea and virt-manager installed. I have one virtual network
defined, and it is set to come up at boot. It does not, apparently
because kea grabs the virtual interface before dnsmasq can grab it.

I have to shut kea's dhcp4 server down, then start the virtual network,
then start the kea dhcp4 server up again.

According to the kea docs, I should be able to tell the kea dhcp4 server
which interfaces to bind to with the "interfaces-config" option. This
does not appear to be working; kea grabs the virtual interface
before dnsmasq can anyway.

This is on trixie as updated.

charles@hawk:~$ pre kea-dhcp4 virt-manager
kea-dhcp4-server	2.6.3-1+deb13u1		amd64
virt-manager	1:5.0.0-5+deb13u1		all
charles@hawk:~$ 

I don't see any relevant reports in
https://bugs.debian.org/cgi-bin/pkgreport.cgi?dist=trixie;package=kea-dhcp4-server

"Dhcp4": {
    // Add names of your network interfaces to listen on.
    "interfaces-config": {
        // See section 8.2.4 for more details. You probably want to add just
        // interface name (e.g. "eth0" or specific IPv4 address on that
        // interface name (e.g. "eth0/192.168.100.12").
        // "interfaces": [ "wlp2s0" ]
        "interfaces": [ "enp3s0" ]

        // Kea DHCPv4 server by default listens using raw sockets. This ensures
        // all packets, including those sent by directly connected clients
        // that don't have IPv4 address yet, are received. However, if your
        // traffic is always relayed, it is often better to use regular
        // UDP sockets. If you want to do that, uncomment this line:
        // "dhcp-socket-type": "udp"
    },