Snowflake SQL Query taking too much time to run when trying to apply multiple joins

At one level GROUPING by all columns is the same as DISTINCT.

But given you are rolling it all up, to only get one of each, you can push the DISTINCTs lower into the queries, and the joins should have not duplicate values

SELECT
    summary._id,
    summary.gep_id,
    summary.ak_cd,
    summary.ak1_cd,
    summary.ak2_cd,
    summary.jj_dt,
    summary.il_ovrd,
    summary.strt_dt,
    summary.event_dt,
    summary.punlication_dt,
    summary.end_dt,
    summary.end_1dt,
    summary.oo_ind,
    summary.expn_dt,
    summary.stathjj_cd,
    summary.stathjj_dt,
    summary.ersk_cd,
    summary.dsrp_nbr,
    summary.lnbr,
    summary.lk_ref,
    summary.ooldesc_cd,
    summary.lmn_cd,
    text.utxct,
    text.gl_cd,
    sb.mn_cd,
    sb.mn_dt,
    sb.evtext,
    sb._start_date,
    sb._end_date,
    re.rronbt,
    re.nn_cd,
    rp.rp_cd,
    rp.rp_t_cd,
    rp.rnme,
    pp.fnbr,
    pp.fdesc_cd,
    ip.fl_dt,
    ip.fl_dttypcd,
    xp.jj_dt,
    xp.oo_cd,
    op.org_ref,
    op.fl_nbr,
    kp.evk_cd,
    kp.evjk_dt
FROM ( 
    SELECT DISTINCT
        summary._id,
        summary.gep_id,
        summary.ak_cd,
        summary.ak1_cd,
        summary.ak2_cd,
        summary.jj_dt,
        summary.il_ovrd,
        summary.strt_dt,
        summary.event_dt,
        summary.punlication_dt,
        summary.end_dt,
        summary.end_1dt,
        summary.oo_ind,
        summary.expn_dt,
        summary.stathjj_cd,
        summary.stathjj_dt,
        summary.ersk_cd,
        summary.dsrp_nbr,
        summary.lnbr,
        summary.lk_ref,
        summary.ooldesc_cd,
        summary.lmn_cd
    FROM prd.post.rr_summ AS summary
) AS summary
LEFT OUTER JOIN (
    SELECT DISTINCT
        text._id
        text.utxct,
        text.gl_cd
    FROM prd.post.yy_textentr AS text
) AS text
    ON text._id = summary._id
LEFT OUTER JOIN (
    SELECT DISTINCT
        sb._id
        sb.mn_cd,
        sb.mn_dt,
        sb.evtext,
        sb._start_date,
        sb._end_date
    FROM prd.post.kk_subevt AS sb
) AS sb
    ON sb._id = summary._id
LEFT OUTER JOIN (
    SELECT DISTINCT
        re._id
        re.rronbt,
        re.nn_cd
    FROM prd.post.lg_nbetr AS re
) AS re
    ON re._id = summary._id
LEFT OUTER JOIN (
    SELECT DISTINCT
        rp._id
        rp.rp_cd,
        rp.rp_t_cd,
        rp.rnme
    FROM    
 prd.post.xx_rpopo AS rp
) AS rp
    ON rp._id = summary._id
 LEFT OUTER JOIN(
    SELECT DISTINCT
        pp._id
        pp.fnbr,
        pp.fdesc_cd
    FROM prd.post.vv_kjiu AS pp
) AS pp
    ON pp._id = summary._id
LEFT OUTER JOIN (
    SELECT DISTINCT
        ip._id
        ip.fl_dt,
        ip.fl_dttypcd
    FROM prd.post.ll_jjhhhip AS ip
) AS ip
    ON ip._id = summary._id
LEFT OUTER JOIN (
    SELECT DISTINCT
        xp._id
        xp.jj_dt,
        xp.oo_cd
    FROM prd.post.uu_ghgghj AS xp
) AS xp  
    ON xp._id = summary._id 
LEFT OUTER JOIN (
    SELECT DISTINCT
        op._id,
        op.org_ref,
        op.fl_nbr
    FROM prd.post.qq_bhbhggg AS op
) AS op
    ON op._id = summary._id
LEFT OUTER JOIN (
    SELECT DISTINCT
        kp._id
        kp.evk_cd,
        kp.evjk_dt
    FROM prd.post.tt_hjhhsy AS kp
) AS kp
    ON kp._id = summary._id;

So this should be much faster.