为什么查询这么慢？因为每次迭代都会将每一行与124个新行连接起来。第二层是124*124行，第四层是236421376行，第七层是450766669594624行。这就是为什么你会得到复制品。也加入双没有影响。
解决办法是纠正错误 connect by 零件，添加条件 wmwhse_id = prior wmwhse_id :

select country, name, wmwhse_id, trunc(sysdate) - level + 1 dt
  from pl_db 
  connect by level <= 7 and prior wmwhse_id = wmwhse_id and prior sys_guid() is not null 
  order by dt desc, wmwhse_id

递归cte在大多数数据库中都是标准的，它更容易实现：

with r(country, name, wmwhse_id, dt, lvl) as (
  select country, name, wmwhse_id, trunc(sysdate), 1 from pl_db union all
  select country, name, wmwhse_id, trunc(sysdate) - lvl, lvl + 1 from r where lvl < 7)
select country, name, wmwhse_id, dt from r;

但最简单的方法是用7个数字进行交叉连接，不管如何生成它们：

select country, name, wmwhse_id, trunc(sysdate) - trim(column_value) + 1 dt
  from pl_db cross join xmltable('1 to 7')

包含所有三个查询的dbfiddle。

除了速度慢之外，您的查询还返回了许多重复项。即使选择不同的值，也不会更快。
但是，像这样的事情可能会发生。我没有你的数据，所以我用cte制作了一个小样本集。

SQL> set timing on
SQL> with pl_db (country, db_alias, db_logid) as
  2    (select 'US', 'CRD2'      , 'AB1' from dual union all
  3     select 'GR', 'WAZ'       , 'CD2' from dual union all
  4     select 'CN', 'KOL'       , 'EF3' from dual union all
  5     select 'FR', 'DEL'       , 'GH4' from dual union all
  6     select 'HR', 'XBPV'      , 'IJ5' from dual union all
  7     select 'AT', 'PRDO'      , 'KL6' from dual union all
  8     select 'DE', 'ENTERPRISE', 'MN7' from dual
  9    )
 10  select
 11    substr(country, 1, 2) as country,
 12    db_alias              as name,
 13    to_number(regexp_replace(db_logid, '[^0-9]', '')) as wmwhse_id,
 14    to_char(sysdate + 1 - column_value, 'yyyymmdd') as actdate
 15  from pl_db cross join
 16    table(cast(multiset(select level from dual
 17                        connect by level <= 7
 18                       ) as sys.odcinumberlist))
 19  where db_alias not like '%BPV'
 20    and db_alias not like 'PRDO%'
 21    and db_alias not like 'ENTERPRISE'
 22  order by actdate desc, wmwhse_id asc;

COUNTRY  NAME        WMWHSE_ID ACTDATE
-------- ---------- ---------- --------
US       CRD2                1 20200604
GR       WAZ                 2 20200604
CN       KOL                 3 20200604
FR       DEL                 4 20200604
US       CRD2                1 20200603
GR       WAZ                 2 20200603
CN       KOL                 3 20200603
FR       DEL                 4 20200603
US       CRD2                1 20200602
GR       WAZ                 2 20200602
CN       KOL                 3 20200602
FR       DEL                 4 20200602
US       CRD2                1 20200601
GR       WAZ                 2 20200601
CN       KOL                 3 20200601
FR       DEL                 4 20200601
US       CRD2                1 20200531
GR       WAZ                 2 20200531
CN       KOL                 3 20200531
FR       DEL                 4 20200531
US       CRD2                1 20200530
GR       WAZ                 2 20200530
CN       KOL                 3 20200530
FR       DEL                 4 20200530
US       CRD2                1 20200529
GR       WAZ                 2 20200529
CN       KOL                 3 20200529
FR       DEL                 4 20200529

28 rows selected.

Elapsed: 00:00:00.09
SQL>

在我看来相当快；试试看，希望对你有帮助。