PostgreSQL 12 will be the minimum required version in GitLab 14.0. It offers [significant improvements](https://www.postgresql.org/about/news/postgresql-12-released-1976/) to indexing, partitioning, and general performance benefits.
Starting in GitLab 13.7, all new installations default to version 12. From GitLab 13.8, single-node instances are automatically upgraded as well. If you aren't ready to upgrade, you can [opt out of automatic upgrades](https://docs.gitlab.com/omnibus/settings/database.html#opt-out-of-automatic-postgresql-upgrades).