Restarting `systemd-networkd` looses unmanaged bridged parents

My home network comprises many VLANs managed by `systemd-networkd`/`netplan`. Those VLANs are then used as parent interfaces for LXD networks. Whenever `systemd-networkd` is restarted (i.e: post-update), my whole network breaks because all the unmanaged bridges lose their parent devices. Another way to see it is that `systemd-networkd` undoes the `master` setting of those VLAN devices.

Here is a simplified reproducer:

1. Create a `vlan1` device

$ lxc launch ubuntu:22.04 networkd-bug
Creating networkd-bug
Starting networkd-bug

$ lxc file push - networkd-bug/etc/netplan/99-vlan1.yaml << EOF
network:
  version: 2
  vlans:
    vlan1:
      id: 1
      link: eth0
EOF

$ lxc exec networkd-bug -- netplan apply

2. Manually create a bridge and join `vlan1` to it

$ lxc exec networkd-bug -- ip link add br0 type bridge
$ lxc exec networkd-bug -- ip link set vlan1 master br0
$ lxc exec networkd-bug -- ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: vlan1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff
3: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 42:b6:31:01:47:9a brd ff:ff:ff:ff:ff:ff
164: eth0@if165: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff link-netnsid 0

3. Restart `systemd-networkd`

$ lxc exec networkd-bug -- systemctl restart systemd-networkd

4. Notice `vlan1` lost it's master config

$ lxc exec networkd-bug -- ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: vlan1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff
3: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 42:b6:31:01:47:9a brd ff:ff:ff:ff:ff:ff
164: eth0@if165: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:94:6e:47 brd ff:ff:ff:ff:ff:ff link-netnsid 0

Ideally, `vlan1` should retain it's `master` setting and I wouldn't loose connectivity :)

Additional information:

# apt-cache policy systemd netplan.io iproute2
systemd:
  Installed: 249.11-0ubuntu3.9
  Candidate: 249.11-0ubuntu3.9
  Version table:
 *** 249.11-0ubuntu3.9 500
        500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     249.11-0ubuntu3.7 500
        500 http://security.ubuntu.com/ubuntu jammy-security/main amd64 Packages
     249.11-0ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages
netplan.io:
  Installed: 0.105-0ubuntu2~22.04.3
  Candidate: 0.105-0ubuntu2~22.04.3
  Version table:
 *** 0.105-0ubuntu2~22.04.3 500
        500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     0.104-0ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages
iproute2:
  Installed: 5.15.0-1ubuntu2
  Candidate: 5.15.0-1ubuntu2
  Version table:
 *** 5.15.0-1ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages
        100 /var/lib/dpkg/status

# lsb_release -rd
Description: Ubuntu 22.04.3 LTS
Release: 22.04
# uname -a
Linux networkd-bug 6.2.0-32-generic #32~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Aug 18 10:40:13 UTC 2 x86_64 x86_64 x86_64 GNU/Linux