I am facing a problem during the upgrade of my release, it is happening that in case I have a release

(example-release contains a list of services...)

Release                                Version
example-release                         0.0.2


example-release service list:
   service1, version 1.1

When I try to upgrade the release with a new chart containing a different version of a service:

helm upgrade --install example-release release-0.0.1.tgz
example-release service list:
   service1, version 1.0

it doesn't remove and reinstall the impacted service to downgrade.

Instead if I execute the following command, it is forced to install:

helm upgrade --install --force example-release release-0.0.1.tgz   

Then the service is reinstalled.
To notice that by executing :

 helm upgrade example-release release-0.0.1.tgz

I don't see any errors, even if the impacted service to downgrade is not touched.

How --force realizes that there is a problem ??

If during an upgrade we install a configmap, should the upgrade to the previous version remove that configmap?

Small update:
Removing the whole release and installing from scratch the upgrade(upgrade/downgrade) of my helm release started to work again without --force, so it sounds like a bug?!? I don't know !

thanks