pico=# select
  count(DISTINCT CASE
    WHEN user_id IS NOT NULL
    THEN 1
 count |         month
-------+------------------------
    26 | 2024-10-01 00:00:00+00
    44 | 2024-09-01 00:00:00+00
    65 | 2024-08-01 00:00:00+00
    56 | 2024-07-01 00:00:00+00
    42 | 2024-06-01 00:00:00+00
    29 | 2024-05-01 00:00:00+00
    36 | 2024-04-01 00:00:00+00
    49 | 2024-03-01 00:00:00+00
    29 | 2024-02-01 00:00:00+00
    21 | 2024-01-01 00:00:00+00
     5 | 2023-12-01 00:00:00+00
    22 | 2023-11-01 00:00:00+00
    31 | 2023-10-01 00:00:00+00
    38 | 2023-09-01 00:00:00+00
    25 | 2023-08-01 00:00:00+00
    43 | 2023-07-01 00:00:00+00
    47 | 2023-06-01 00:00:00+00
    29 | 2023-05-01 00:00:00+00
    33 | 2023-04-01 00:00:00+00
    39 | 2023-03-01 00:00:00+00
    41 | 2023-02-01 00:00:00+00
    49 | 2023-01-01 00:00:00+00
    52 | 2022-12-01 00:00:00+00
    53 | 2022-11-01 00:00:00+00
    58 | 2022-10-01 00:00:00+00
    62 | 2022-09-01 00:00:00+00
   591 | 2022-08-01 00:00:00+00