If an octavia loadbalancer is created with OVN provider, on a provider network which has dual-stack (ipv4 and ipv6 subnets), the next error happens:

2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper [-] Exception occurred during creation of loadbalancer: ValueError: IPAddress() does not support netmasks or subnet prefixes! See documentation for details.
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper Traceback (most recent call last):
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper File "/usr/lib/python3.6/site-packages/netaddr/ip/__init__.py", line 803, in parse_ip_network
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper prefixlen = int(val2)
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper ValueError: invalid literal for int() with base 10: '24 2001:db8::f816:3eff:fed5:a9e1/64'
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper During handling of the above exception, another exception occurred:
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper Traceback (most recent call last):
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper File "/usr/lib/python3.6/site-packages/ovn_octavia_provider/helper.py", line 873, in lb_create
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper ovn_lr = self._find_lr_of_ls(ovn_ls, subnet.get('gateway_ip'))
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper File "/usr/lib/python3.6/site-packages/ovn_octavia_provider/helper.py", line 640, in _find_lr_of_ls
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper port.external_ids['neutron:cidrs']).ip
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper File "/usr/lib/python3.6/site-packages/netaddr/ip/__init__.py", line 928, in __init__
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper implicit_prefix, flags)
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper File "/usr/lib/python3.6/site-packages/netaddr/ip/__init__.py", line 810, in parse_ip_network
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper mask = IPAddress(val2, module.version, flags=INET_PTON)
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper File "/usr/lib/python3.6/site-packages/netaddr/ip/__init__.py", line 280, in __init__
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper % self.__class__.__name__)
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper ValueError: IPAddress() does not support netmasks or subnet prefixes! See documentation for details.
2022-02-03 09:19:04.234 12 ERROR ovn_octavia_provider.helper
2022-02-03 09:19:04.942 12 WARNING ovn_octavia_provider.helper [-] Deleting the VIP port 7b6bc45c-ff51-45e3-81ef-7b596528ff44 since LB went into ERROR state

This is due to logical ports associated to the provider network logical switch have both ipv4 and ipv6 into the "neutron:cidrs" field at external_ids:
ovn-nbctl list logical_switch_port 0016d6d0-b8cb-4542-b6fe-840740eef9f0
_uuid : 0016d6d0-b8cb-4542-b6fe-840740eef9f0
addresses : [router]
dhcpv4_options : []
dhcpv6_options : []
dynamic_addresses : []
enabled : true
external_ids : {"neutron:cidrs"="172.24.100.198/24 2001:db8::f816:3eff:fed5:a9e1/64", "neutron:device_id"="142845e4-3424-4b19-a02a-6bfed63efb8f", "neutron:device_owner"="network:router_gateway", "neutron:network_name"=neutron-b1f7e9be-2c18-4f68-9253-ca2bcbb904a1, "neutron:port_name"="", "neutron:project_id"="", "neutron:revision_number"="5", "neutron:security_group_ids"="", "neutron_bgpvpn:as"="64999", "neutron_bgpvpn:vni"="1001"}
ha_chassis_group : []
name : "6b7aa199-b715-4585-a88b-30f276961995"
options : {nat-addresses=router, router-port=lrp-6b7aa199-b715-4585-a88b-30f276961995}
parent_name : []
port_security : []
tag : []
tag_request : []
type : router
up : true