Query is very slow

Oracle product : oracle database 19c

Oracle version : oracle Database 19.16.0.0

OS version : RHEL 8

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SELECT

 SOCRATES.APPLICATIONS.PROJECT_NUMBER,

 CASE WHEN EREP_OBJECTS.OBJECT_TYPE IN ('CBB')THEN STATISTICS_CBT_VALUES.DOMAIN_VALUE_LABEL WHEN EREP_OBJECTS.OBJECT_TYPE NOT IN ('TBL') AND EREP_OBJECTS.OBJECT_TYPE NOT IN ('CBB')THEN

STATISTICS_VALUE.STATISTICS_VALUE END,

 EREP_OBJECTS.OBJECT_ORDER,

 EREP_OBJECTS.OBJECT_LABEL,

 EREP_OBJECTS.OBJECT_CODE,

 PARENT_OBJECT.OBJECT_LABEL,

 PARENT_OBJECT.OBJECT_CODE

FROM

 ( 

 SELECT V.*, O.*, CASE WHEN O.TABCOL_ID IS NULL THEN O.OBJECT_ID ELSE O.TABCOL_ID END TABCOL_KEY FROM

(SELECT D.DOMAIN_OBJECT_ID, D.ID_SMART_COMBO, D.OBJECT_ID, D.PHASE_ID, D.ROUND_ID, D.TABCOL_ID,