Various .NET installer packages are not cleaning up the package provider keys in the registry:

This can impact installation time and even Windows startup time (at least in older versions; not sure if that's currently the case). A package should clean up it's provider key when uninstalled/upgraded.

For context, I was the creator of the package reference tracking feature first introduced in WiX and implemented later in the Visual Studio Installer. I'm working on some general documentation for how it works and expected behaviors of chainers and packages alike, but for now the main thing is that a package should clean up it's provider key and any dependencies it registers on other packages - the latter of which is crucial to be able to uninstall packages once the non-identity package dependencies are all removed.