Usually, once you upgraded Postgres clusters, you would need to run ANALYZE on the whole cluster to make sure that the database statistics are up to date. Because you know that not doing it will make your database performance go VERY bad.

And if you use pg_upgrade to perform the upgrade, there is a tiny little script you can call to do this analyze process, named in Linux and Unix environment and analyze_new_cluster.bat in Windows. It is useful if you use automation system, such as Ansible, because you just need to call this tiny little thing.

But, the script is no longer there if you upgraded to PostgreSQL 14. Yes, the file is removed.[1]

Why? Because that file only contains some comments and one other line calling vacuumdb command.

So, if you have a playbook, Ansible playbook or simple script, calling this file, remember to change it to vacuumdb --all --analyze-in-stages for upgrading to Postgres 14.