lateral join with union all

select * from
(
(select 2 as v )
union all
(select 3 as v)
) as q1
cross join lateral
( (select * from
((select 4 as v) union all
(select 5 as v)) as q3
)
union all
(select q1.v)
) as q2;

I thought q1 will be materialized as a constant set and will be equivalent
as select 2 union all select 3;
Then It will have 8 (2 * 4) rows total. Then It will be like {2,3} cross
join with {2,3,4,5}

But Here the actual result(return 6 rows) feels like two separate
queries(A,B) then union together.
QueryA: (select 2 as v ) cross join lateral (.....)
QueryB: (select 3 as v ) cross join lateral (.....)
Query A 3 row + Query B 3 row. So the total is 6 rows.

Then I feel a little bit confused.

--
I recommend David Deutsch's <<The Beginning of Infinity>>

Jian