Yes, MSSQL for example is self contained OS or container image updates aren’t going to impact it or at least it’s extremely unlikely that they will.

Postgres is dependent on a lot of OS level C libraries that can materially change how things work.

This means that there will have to be more testing with Postgres and there will be higher uncertainty between different deployments.

All of these can be mitigated and for many organizations the benefits of Postgres might outweigh these downsides but they do exist.