new.sql

with uuids_by_party_id as (
	select p."uuid"
	from register.party p
	where p.id = any (:partyids)
), uuids_by_user_id as (
	select u."uuid"
	from register."user" u
	where u.user_id = any (:userids)
), uuids as (
	select "uuid"
	from uuids_by_party_id
	union
	select "uuid"
	from uuids_by_user_id
)
select
	p.uuid p_uuid,
    p.id p_id,
    p.party_type p_party_type,
    p.display_name p_display_name,
    p.person_identifier p_person_identifier,
    p.organization_identifier p_organization_identifier,
    u.user_id,
    u.is_active
from register.party p
left join register."user" u using (uuid)
where p."uuid" in (select "uuid" from uuids)
order by p.uuid, u.is_active DESC, u.user_id desc

old.sql

SELECT
    p.uuid p_uuid,
    p.id p_id,
    p.party_type p_party_type,
    p.display_name p_display_name,
    p.person_identifier p_person_identifier,
    p.organization_identifier p_organization_identifier,
    ua.user_ids u_user_ids
FROM register.party p
LEFT JOIN (
    SELECT
        u.uuid,
        array_agg(u.user_id ORDER BY u.is_active DESC, u.user_id DESC) AS user_ids
    FROM register.user u
    WHERE u.is_active OR u.user_id = ANY (:userids)
    GROUP BY u.uuid
) ua USING (uuid)
WHERE (
       p.id = ANY(:partyids)
    OR :userids && ua.user_ids
)
ORDER BY p.uuid