here how excess indexes can be found, excess mean that there is a single column index which is covered by first value of complex index

select * from (
select count(*),pg_size_pretty(pg_relation_size(t.table_name)),t.table_name,t.indkey_names[1],min(array_length(t.indkey_names,1)) min_index_elements_cnt from (
SELECT i.relname as indname,
       i.relowner as indowner,
       idx.indrelid::regclass table_name,
       idx.indkey,
       ARRAY(
       SELECT pg_get_indexdef(idx.indexrelid, k + 1, true)
       FROM generate_subscripts(idx.indkey, 1) as k
       ORDER BY k
       ) as indkey_names,
       idx.indexprs IS NOT NULL as indexprs,
       idx.indpred IS NOT NULL as indpred
FROM   pg_index as idx
JOIN   pg_class as i
ON     i.oid = idx.indexrelid
where idx.indrelid::text not like 'pg_toast%' 
and pg_relation_size(indexrelid::regclass)>100*1024*1024 ) t
group by t.indkey_names[1],t.table_name
having count (*) >1
) tt where min_index_elements_cnt =1;