Skipping sequence values in PostgreSQL

psql-sequences.log

[local] owenja@owenja=> create temporary table demo (id integer primary key generated always as identity, value text);
CREATE TABLE
[local] owenja@owenja=> insert into demo (value) values ('a');
INSERT 0 1
[local] owenja@owenja=> select * from demo;
 id | value 
----+-------
  1 | a
(1 row)

[local] owenja@owenja=> begin;
BEGIN
[local] owenja@owenja=> insert into demo (value) values ('about to be rolled back') returning id;
 id 
----
  2
(1 row)

INSERT 0 1
[local] owenja@owenja=> rollback;
ROLLBACK
[local] owenja@owenja=> insert into demo (value) values ('about to be committed') returning id;
 id 
----
  3
(1 row)

INSERT 0 1
[local] owenja@owenja=> select * from demo;
 id |         value         
----+-----------------------
  1 | a
  3 | about to be committed
(2 rows)

[local] owenja@owenja=> alter table demo add check ((id % 2) = 1);
ALTER TABLE
[local] owenja@owenja=> insert into demo (value) values ('fails check constraint') returning id;
ERROR:  23514: new row for relation "demo" violates check constraint "demo_id_check"
DETAIL:  Failing row contains (4, fails check constraint).
SCHEMA NAME:  pg_temp_4
TABLE NAME:  demo
CONSTRAINT NAME:  demo_id_check
LOCATION:  ExecConstraints, execMain.c:2003
[local] owenja@owenja=> insert into demo (value) values ('passes check constraint') returning id;
 id 
----
  5
(1 row)

INSERT 0 1