function in runs-on doesn't work

Describe the bug

I have the workflow listen on event deployment for app deployment.
I'd like to reuse the same workflow for both nonprod and prod.
that means i have to use variable as runner label in runs-on statement.
however, runs-on doesn't support func call:
Not work
runs-on: ["${{ fromJson(github.event.deployment.payload).runnerLabel }}"] results in runs-on: [""]
Work
runs-on: ["${{ github.event.deployment.description }}"] results in runs-on: ["prod"]
assume description has the right runner label value

To Reproduce
Steps to reproduce the behavior:

name: CD

on: ['deployment']

jobs:
  deploy:
    name: Deploy
    runs-on: ["${{ fromJson(github.event.deployment.payload).runnerLabel }}"]
    steps:
      ...

the workflow failed says no runner matched. "${{ fromJson(github.event.deployment.payload).runnerLabel }}" results in an empty string.

Expected behavior
expect the value being correctly extracted from json, like runs-on: ["prod"]

Runner Version and Platform

Version of your runner?

2.273.5

OS of the machine running the runner? OSX/Windows/Linux/...

Ubuntu 20.04

What's not working?

Please include error messages and screenshots.

Job Log Output

N/A

Runner and Worker's Diagnostic Logs

N/A

Start by reproducing the deployment-triggered workflow from the issue using runner version 2.273.5 and compare the fromJson expression with the direct description value in runs-on. Trace the runner's workflow-expression handling to determine why runnerLabel becomes empty; done when the JSON value resolves to a runner label and the job selects the expected runner.