Unfortunately, the description you provided does not contain sufficient details for us to reproduce the issue. Please consider describing the issue per our problem reporting guidelines so that we could try reproducing it on our side.
Thanks for the repro steps. We have reproduced the problem, however it looks like it’s limited to showing incorrect value in the status bar. Indeed, canceling an Arduino package installation will immediately stop the download, but the Visual Studio’s status bar will only get updated when another component uses it to display the progress.
Due to the relatively low impact of the issue, we will fix it during the next update of the progress-related logic.