Calculating time intervals considering business days and 24x7

I have the following Postgresql structure and data :

CREATE TABLE requests (
    entity_id INTEGER,
    type_de_demande TEXT,
    phase TEXT,
    time BIGINT,
    next_time BIGINT
);

INSERT INTO requests (entity_id, type_de_demande, phase, time, next_time)
VALUES
	(3402670, 'SUPPORTREQUEST', 'Log', 1684836635813, 1684836637569),
	(3402670, 'SUPPORTREQUEST', 'Classify', 1684836637569, 1684836638257),
	(3402670, 'SUPPORTREQUEST', 'FirstLineSupport', 1684836638257, 1685090241035),
	(3402670, 'SUPPORTREQUEST', 'Escalate', 1685090241035, 1685090241833),
	(3402670, 'SUPPORTREQUEST', 'Close', 1685090241833, NULL)

The objective is to calculate the time interval between "time" and "next_time" in business time (excluding Saturday and Sunday) and 24x7 time. Currently, I am able to obtain the correct interval for 24x7 time, but for the business interval, I am getting incorrect values.

Here is my SQL select query :

SELECT
	t.entity_id,
    t.type_de_demande,
    t.phase,
    bd.bus_interval,
    bd.interval_24x7,
    ts.start_ts,
    ts.end_ts,
    t.time,
    t.next_time
FROM requests AS t
inner join lateral (
	SELECT 
    	to_timestamp(t.time / 1000)::timestamp      AS start_ts,
        to_timestamp(t.next_time / 1000)::timestamp AS end_ts,
        (SELECT COUNT(*)::int 
         FROM generate_series(to_timestamp(t.time / 1000)::DATE, to_timestamp(t.next_time / 1000)::DATE, '1 day')
         WHERE EXTRACT(ISODOW FROM generate_series) < 6
        ) AS bus_days
) AS ts ON true
inner join lateral (
    SELECT 
        ts.end_ts - ts.start_ts as interval_24x7,
        make_interval(0,0,0,ts.bus_days - 1) + ((ts.end_ts - ts.start_ts)::time)::interval  as bus_interval
) as bd on true

Result :

Why does the bus_interval column have an additional day {"days":3,"hours":22,"minutes":26,"seconds":43} instead of the expected value of {"days":2,"hours":22,"minutes":26,"seconds":43}? Is there another method to calculate the interval between two Unix timestamps considering both business days and 24x7 time?

Fiddle: https://www.db-fiddle.com/f/axnWR8TUupXywi1ddHDHtX/0

I think your bus_days sub query should be like following. I have removed ::DATE cast and also including generate_series timestamp only when its less than or equal to t.next_time.

(SELECT COUNT(*)::int 
         FROM generate_series(to_timestamp(t.time / 1000), to_timestamp(t.next_time / 1000), '1 day')
         WHERE generate_series <= to_timestamp(t.next_time / 1000) AND EXTRACT(ISODOW FROM generate_series) < 6
        ) AS bus_days