Output of helm version:
version.BuildInfo{Version:"v3.5.0", GitCommit:"32c22239423b3b4ba6706d450bd044baffdcf9e6", GitTreeState:"clean", GoVersion:"go1.15.6"}

Output of kubectl version:
Client Version: version.Info{Major:"1", Minor:"20", GitVersion:"v1.20.5", GitCommit:"6b1d87acf3c8253c123756b9e61dac642678305f", GitTreeState:"clean", BuildDate:"2021-03-18T01:10:43Z", GoVersion:"go1.15.8", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.10+IKS", GitCommit:"625e0232c45f878423cb1285322bf54ad8a3993f", GitTreeState:"clean", BuildDate:"2021-04-20T22:44:26Z", GoVersion:"go1.15.10", Compiler:"gc", Platform:"linux/amd64"}

Cloud Provider/Platform (AKS, GKE, Minikube etc.): Any cloud

Description:
I have been trying to nullify values in sub chart that are passed via global section in values.yaml.

values.yaml

global:
  sub1:
    key: value

When I use this in the subchart x as .Values.global.sub1.key, it works perfectly fine. I can also override it using --set global.sub1.key=newValue. However, when I try to nullify the value, it fetches the default value from the actual values.yaml.

i.e --set global.sub1.key=null, it still fetches the default value from the original values.yaml.

Please let me know if you need any additional information.