Hello,
According to the documentation, creating a row-level trigger on a partitioned table will cause identical triggers to be created in all its existing partitions; and any partitions created or attached later will contain an identical trigger, too.
It does not happen for a sub-partition - partition of partition - when it is created/attached later. Steps to reproduce (11.6, Centos 7):
create table level1 (id1 integer not null, id2 integer not null, id3 integer not null) partition by list (id2);
create table level2 partition of level1 for values in (1) partition by list (id3);
create table level3 partition of level2 for values in (1);
create or replace function trigger_func() returns trigger language 'plpgsql' as $body$ begin raise exception 'fired'; return null; end $body$;
create trigger test_trigger after insert on level1 for each row execute procedure trigger_func();
insert into level1 values (1,1,1); -- fails as expected due to test_trigger();
drop table level1;
drop function trigger_func();
create table level1 (id1 integer not null, id2 integer not null, id3 integer not null) partition by list (id2);
create or replace function trigger_func() returns trigger language 'plpgsql' as $body$ begin raise exception 'fired'; return null; end $body$;
create trigger test_trigger after insert on level1 for each row execute procedure trigger_func();
create table level2 partition of level1 for values in (1) partition by list (id3);
create table level3 partition of level2 for values in (1);
insert into level1 values (1,1,1); -- row inserted
psql \d+ shows that level3 does not have row level trigger while level2 and level1 have.