Ubuntu 23.10 KVM /etc/netplan/01-netcfg.yaml

network:
  version: 2
  renderer: NetworkManager
  ethernets:
    enx00e04d711639:
      dhcp4: false
      dhcp6: false
      mtu: 9000
  bridges:
    br0:
      interfaces: [enx00e04d711639]
      addresses:
        - 192.168.3.99/24
      routes:
        - to: default
          via: 192.168.3.1
      nameservers:
        addresses:
          - 192.168.3.1
      dhcp4: false
      dhcp6: true
      parameters:
        stp: true
        forward-delay: 4

Save yourself a lot of headaches and install yamllint and use it on your configs. Once changes are verified run netplan apply . networkctl will show status.