KeyVault variable usage inside Bash Task in Azure Pipeline

Question

Recently I am facing problem with my variable containing secret from KeyVault.

I am retrieving ssh keys from KeyVault with following code and this works fine (in this case there is only one key under kv_key_list variable - ansibleprvk but there also could be few of them):

- task: AzureKeyVault@2
  displayName: Retrieve SSH Keys from KeyVault
  inputs:
    azureSubscription: ${{ parameters.ADO_subscription }}
    KeyVaultName: ${{ parameters.ADO_vaultName }}
    SecretsFilter: $(kv_key_list)
    RunAsPreJob: false

Now i need to interate over kv_key_list and save each key to temp file but that is not the case.

Right now i just want to print out this secret to pipeline and i can achieve this by hardcoding keyname like this:

- task: Bash@3
  displayName: Store ssh key
  inputs:
    targetType: 'inline'
    script: |
      echo -e "$(ansibleprvk)" | base64 -d

Mentioned code prints out whole SSH Key to teh pipeline.

Knowig that uder my variable there is only one keyname i want to replace hardcoded ansibleprvk with variable like in following code but this prints out nothing:

- task: Bash@3
  displayName: Store ssh key
  inputs:
    targetType: 'inline'
    script: |
      echo -e "$($(kv_key_list))" | base64 -d

What am i doing wrong? how to replace hardcoded string with variable?