Found a "fix" from github for the project. The case requirements changed so that everything after HOMECHART_ must be lower case. More details here Config | Homechart
You should have:
HOMECHART_postgresql_hostname
HOMECHART_postgresql_password
HOMECHART_postgresql_username
HOMECHART_postgresql_port
HOMECHART_postgresql_database
Also, I had to make a couple of commands on the database due to changes in postgresql 15 (more detail here https://stackoverflow.com/a/74111630)
GRANT ALL ON DATABASE homechart TO homechart;
ALTER DATABASE homechart OWNER TO homechart;
After that my instance started correctly