Access after variables are injected

Is it possible to access the object in the Pre-request Script section after variables are injected?

Use Case: Hash, which is JSON that contains Postman variables. I am then using this hashed value in a request header (required for authentication).

Problem: When I attempt to hash the it hashes the Postman variable instead of the value.

Environment variables
my_postman_variable = someUserId

Example JSON
{ “userId”: {{my_postman_variable}} }

Expected output = { “userId”: “someUserId” }

Actual output = { “userId”: {{my_postman_variable}} }

Is there no answer for this?

Would it be possible for you to share your Pre-Request Script here so we can have a little more context for what you’re doing?