buster works:

auto lo
iface lo inet loopback

allow-ovs ovsbr0
iface ovsbr0 inet static
    address 10.10.189.3
    netmask 255.255.255.192
    broadcast 10.10.189.63
    gateway 10.10.189.1
    ovs_type OVSBridge
    ovs_ports eno1

auto eno1
allow-ovsbr0 eno1
iface eno1 inet manual
    ovs_bridge ovsbr0
    ovs_type OVSPort

bullseye works:
auto lo
iface lo inet loopback

allow-ovs ovsbr0
iface ovsbr0 inet static
    address 10.10.189.3
    netmask 255.255.255.192
    broadcast 10.10.189.63
    gateway 10.10.189.1
    ovs_type OVSBridge
    ovs_ports eno1

auto eno1
allow-ovsbr0 eno1
iface eno1 inet manual
    ovs_bridge ovsbr0
    ovs_type OVSPort
    post-up ifup ovsbr0
    post-down ifdown ovsbr0