Unbound's dhcp-leases.conf disappears

No, I greped for “leases” or “brigde” (grep -i …) but nothing except

Sep  8 10:26:22 igel3 dhcp[1121]: Unbound DHCP Leases Bridge started on /var/state/dhcp/dhcpd.leases
Sep  8 10:28:16 igel3 dhcp[1259]: Unbound DHCP Leases Bridge started on /var/state/dhcp/dhcpd.leases
Sep  8 16:43:34 igel3 dhcp[16208]: Unbound DHCP Leases Bridge started on /var/state/dhcp/dhcpd.leases
Sep  8 16:44:58 igel3 dhcp[16324]: Unbound DHCP Leases Bridge started on /var/state/dhcp/dhcpd.leases

…which was when I restarted dhcp.

Following this thread i did add the verbose flag to the Start line of this leases bridge in /etc/init.d/dhcp, i e.

loadproc /usr/sbin/unbound-dhcp-leases-bridge -d -vv

This is the log output in messages after dhcp restart:

Sep  8 16:53:06 ipfire dhcp[16754]: Unbound DHCP Leases Bridge started on /var/state/dhcp/dhcpd.leases
Sep  8 16:53:06 ipfire dhcp[16754]: Wakeup of main loop
Sep  8 16:53:07 ipfire dhcp[16754]: Reading static hosts from /var/ipfire/main/hosts
Sep  8 16:53:07 ipfire dhcp[16754]: Static hosts:
Sep  8 16:53:07 ipfire dhcp[16754]:   host1.example.com    : 192.168.0.8
Sep  8 16:53:07 ipfire dhcp[16754]:   host2.example.com     : 192.168.0.7
Sep  8 16:53:07 ipfire dhcp[16754]:   my-printer.example.com : 192.168.0.211
   some more hosts...
Sep  8 16:53:07 ipfire dhcp[16754]: Reading DHCP leases from /var/state/dhcp/dhcpd.leases
Sep  8 16:53:07 ipfire dhcp[16754]: Reading fix leases from /var/ipfire/dhcp/fixleases
Sep  8 16:53:07 ipfire dhcp[16754]: DHCP Leases:
Sep  8 16:53:07 ipfire dhcp[16754]:   host3.example.com:
Sep  8 16:53:07 ipfire dhcp[16754]:     State: active
Sep  8 16:53:07 ipfire dhcp[16754]:     Start: 2024-09-08 14:53:07
Sep  8 16:53:07 ipfire dhcp[16754]:     End  : None
Sep  8 16:53:07 ipfire dhcp[16754]:   host4.example.com:
Sep  8 16:53:07 ipfire dhcp[16754]:     State: active
Sep  8 16:53:07 ipfire dhcp[16754]:     Start: 2024-09-08 14:53:07
Sep  8 16:53:07 ipfire dhcp[16754]:     End  : None
Sep  8 16:53:07 ipfire dhcp[16754]:   None:
Sep  8 16:53:07 ipfire dhcp[16754]:     State: active
Sep  8 16:53:07 ipfire dhcp[16754]:     Start: 2024-09-08 14:53:07
Sep  8 16:53:07 ipfire dhcp[16754]:     End  : None
Sep  8 16:53:07 ipfire dhcp[16754]:   host5.example.com:
Sep  8 16:53:07 ipfire dhcp[16754]:     State: active
Sep  8 16:53:07 ipfire dhcp[16754]:     Start: 2024-09-08 14:53:07
Sep  8 16:53:07 ipfire dhcp[16754]:     End  : None
 some more hosts...
Sep  8 16:53:07 ipfire dhcp[16754]: Writing DHCP leases...

What does None mean in the list of fixed leases?