take this with a grain of salt - pigsty is a "free rds alternative" and obviously biased towards talking k8s + postgres bad.
Which is funny as we are way past old "Kubernetes for databases bad" and postgress has a wide selection of decent operators that manage whole DB life cycle, replication, backups...
It's a pretty dense space already (which is great).
said that i still see teams keeping Postgres running on VMs because its easy to maintain, to troubleshoot, to fine tune and to restore after a catastrophe..
Gitlab is something as well that i keep seeing, if on premise and not AWS, regardless of having a k8s, they prefer to have it on a VM.