Terraform: make immutalbe environment

Looking for help to address following issue.

When sequentially running tg plan & tg apply & tg plan both plans always showing the environment changes.

Sometimes it's clear when resources are some timestamps or null_resources. Sometimes not very e.g: data or some jsonencode function. And sometimes it's not clear at all when you not in context, e.g: gateway_deployemnt_id:

There must some anti-pattern or list of resources we should try avoid to use but I can't find it.