BUG #18160: first create table show "ERROR: permission denied for schema public", next create table works

The following bug has been logged on the website:

Bug reference: 18160
Logged by: Pawel Ziewiecki
Email address: pawel(dot)ziewiecki(at)gmail(dot)com
PostgreSQL version: 15.3
Operating system: aws rds postgresql
Description:

create table (failed) + alter table (table not exist) + create table success
in public schema (?)

psql -h database-imenago.cahxcxwmeghl.eu-central-1.rds.amazonaws.com -p 5432
-U postgres
Password for user postgres:
psql (15.4 (Debian 15.4-1.pgdg120+1), server 15.3)
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384,
compression: off)
Type "help" for help.

postgres=> create user u1 with createdb password 'u1pwd';
CREATE ROLE
postgres=> \c postgres u1
Password for user u1:
psql (15.4 (Debian 15.4-1.pgdg120+1), server 15.3)
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384,
compression: off)
You are now connected to database "postgres" as user "u1".
postgres=> create database u1db with owner u1;
CREATE DATABASE
postgres=> \c u1db
psql (15.4 (Debian 15.4-1.pgdg120+1), server 15.3)
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384,
compression: off)
You are now connected to database "u1db" as user "u1".
u1db=> create table public.t1 (id int);
ERROR: permission denied for schema public
LINE 1: create table public.t1 (id int);
^
u1db=> alter table public.t1 owner to u1;
ERROR: relation "public.t1" does not exist
u1db=> create table public.t1 (id int);
CREATE TABLE
u1db=> \d
List of relations
Schema | Name | Type | Owner
--------+------+-------+-------
public | t1 | table | u1
(1 row)