Test Case:
Create Test Table and Insert Sample Data:
CREATE TABLE t1 (
  value integer
);

INSERT INTO t1 VALUES (1),(2),(3);

Query1:
select  
  ref_1.value as c_0, 
  ref_2.value as c_1
from 
  (t1 as ref_1
    full outer join generate_series(1, 3, 1) as ref_2
    on (ref_1.value = ref_2.value ));

Expected Result:
1|1
2|2
3|3

Actual Result:
1|1
2|2
3|3
|2
|3

Query2:
select  
  ref_1.value as c_0, 
  ref_2.value as c_1
from 
  (t1 as ref_1
    right outer join generate_series(1, 3, 1) as ref_2
    on (ref_1.value = ref_2.value ));

Expected Result:
1|1
2|2
3|3

Actual Result:
1|1
2|2
3|3
|2
|3

SQLite Version:
3.50.0 2025-03-12 15:17:13 6ec0c03b954cf705da076d035a1cc2e784233ae28857385379e44a59af6c5ec4 (64-bit)