FileInUse false positive

[mikehenselersimfront]

We are trying to uninstall our product and we get FileInUse for other apps that are running that are not ours.
(example teams and GitExtensions.)
We discovered for example GitExtensions is using Newtonsoft.Json.dll that exists in GitExtension INSTALLDIR and processexplorer shows GitExtensions is using it from there.

We also deploy Newtonsoft.Json.dll in our INSTALLDIR used by our service.
onUninstall i am forcing myservice to stop before InstallValidate, but we still get a FileInUse for GitExtensions.

I also have "MSIRESTARTMANAGERCONTROL" = "Disable"

Why is FileInUse picking on our copy of Newtonsoft.Json.dll
is there a way to prevent this from happening?
thnks

from MSI log:
Info 1603.The file C:\Program Files\myservice\Newtonsoft.Json.dll is being held in use by the following process: Name: GitExtensions, Id: 3016, Window Title: '(not determined yet)'. Close that application and retry.