Retrospectively pulling number of users each calendar month

Community Building Data & reporting
2

This data explorer query will return unique monthly user visits. Is that what you want?

--[params]
-- date :start_date = 2021-01-01
-- date :end_date = 2021-12-31
-- string_list :group_name = staff,admins

WITH not_allowed_groups AS (
    SELECT gu.user_id FROM group_users gu
    INNER JOIN groups g ON (g.id = gu.group_id)
    WHERE g.name IN (:group_name) 
)

SELECT 
    to_char(date_trunc('month', uv.visited_at)::DATE,'YYYY-MM') AS "month",
    date_trunc('month', uv.visited_at)::DATE AS date_user_visits,
    COUNT(distinct uv.user_id) AS qtt_user_visits
FROM user_visits uv
WHERE
    uv.user_id NOT IN (SELECT user_id FROM not_allowed_groups)
    AND uv.visited_at::DATE BETWEEN :start_date AND :end_date
GROUP BY date_trunc('month', uv.visited_at)::DATE
ORDER BY date_trunc('month', uv.visited_at)::DATE