helm --set .Values.someProp=false isnt overriding the default true value given in values.yaml

I have a helm chart that is used as a subchart\base chart for a microservice chart we call it common.

the microservice chart looks like this when it uses common(each MS can deploy x pods using x deployments created by it's chart):

apiVersion: v2
name: charts-integration-test
description: testing the common chart integration
dependencies:
  - alias: app-01
    name: common
    repository: file://../../
    version: ~2
  - alias: app-02
    name: common
    repository: file://../../
    version: ~2
  - alias: app-02-internal
    name: common
    repository: file://../../
    version: ~2
  - alias: app-02-internal-bluegreen
    name: common
    repository: file://../../
    version: ~2    

and the values.yaml of this microservice looks like this:

global:
  application:
    imageName: foo
    imageTag: bar
    envVariables: {}
    rookout:
      enabled: false
    config:
      logLevel: INFO
      foodb:
        fooDbName: fooDbName
        fooDbHost: fooDbHost

applications:
  - app-01
  - app-02 

app-01:
  config:
    foodb:
      fooDbName: fooDbName2
      fooDbHost: fooDbHost2

in this common chart in my values.yaml file I have the following value:

commonDefaults:
  rookout:
    enabled: true

in my deployment.yaml for this chart I am merging the values of 2 values.yaml using the following code:

{{- $values := merge (.Values | deepCopy) (.Values.global.application | deepCopy) (.Values.commonDefaults | deepCopy) -}}

The point being that in this example, .Values.commonDefaults is being overriden by .Values.global.application and both are overriden by .Values which in this case is values set in the MS values.yaml under app-01.

The thing is that global.application.rookout.enabled=false is not overriding commonDefaults.rookout.enabled=true. Even though it works if I put global.application.rookout.enabled=foobar, in which case it does override as expected.

I am using helm version 3.8.2 although it doesn't work with 3.12.2 as well.

Helm is appreciated.

For whoever finds this question relevant for the helm use-case they are struggling with here goes:

It's not possible. The GO spring templating language treats the value someKey: false as undefined.

So, if you have a default value someKey: true and you are trying to override it with an undefined value i.e. --set someKey=false then helm will not change the default value because you don't override a value with an undefined value.

My solution was to change all the logic in my helm chart to "true" and "false" so instead of: {{ if .Values.someKey }} I use {{ if eq .Values.someKey "true" }}

And when I want to override it in the cli I do --set-string someKey=false

it's not nice but it's what it is.