create table bureau
(
report_key number,
bureau_date date
)
;

insert into bureau
   (report_key, bureau_date)
 values
   (1, to_date('15/07/2020', 'dd/mm/yyyy'));
insert into bureau
   (report_key, bureau_date)
 values
   (2, to_date('01/05/2020', 'dd/mm/yyyy'));
commit
;

--не получилось развернуть pivot-ом, нужны динамические именования столбцов (хардкодом их добавлять не вариант)
select distinct
    report_key, bureau_date, add_months(bureau_date,-level) as prev_months, level as rn, 'cut_date_'||level as field_name
from BUREAU b
connect by
    prior report_key = report_key and
    prior bureau_date = bureau_date and
    prior dbms_random.value is not null and
    level between 1 and 10
  order by report_key, bureau_date, 4
;

--не тот вид, что ожидаю
with dates as (
 select distinct
    report_key, bureau_date, add_months(bureau_date,-level) as cut_date, level as rn, 'cut_date_'||level as field_name
from BUREAU b
connect by
    prior report_key = report_key and
    prior bureau_date = bureau_date and
    prior dbms_random.value is not null and
    level between 1 and 10
  order by report_key, bureau_date, 4)
select distinct *
from dates
  pivot xml(min(cut_date) for(field_name) in (select distinct field_name from dates)) 
;