The timestamptz data type is horrible advice.

It is not actually a data type, it's just timezone but the database will convert what you send to UTC. Any time a database decides to store something different than what you provide will be an endless source of bugs. It also doesn't store the timezone so you need a separate column for that anyway if necessary.

Use normal `timestamp`. Always use UTC in your code for any "instant in time" and a separate column for user-facing appointment scheduling.