In my Python/Postgres application on Railway, I recently completed a timezone migration that involved converting a DATE column to TIMESTAMPTZ and enforcing a constraint to store all dates as midnight UTC. During the migration, I ran into several issues including existing data violating the UTC constraint, application code inconsistencies with date formatting, and PostgreSQL session timezone defaults interfering with comparisons. After extensive debugging, I resolved it by standardizing on UTC conversions, updating queries to explicitly compare in UTC, and fixing date parsing in the application logic.

Now that Railway is moving to Metal, do I need to worry about any regressions or differences in how session timezones or TIMESTAMPTZ are handled?

Specifically, will the underlying system timezone, environment variables, or Postgres configuration differ from the current setup and affect how timestamps behave?