Since Unity 2020.1.15f1, the Package Manager shows me new versions of packages, but I cannot download them because it appears to me as already downloaded. But I have not downloaded these new versions and the file is still displayed on my hard drive with the old date and content. This is also the case in Unity 2020.1.16f1. Here is a screenshot of the Package Manager, the file on the hard drive in Explorer and the opened file in an editor with the version number in the JSON part. This only affects the packages from the Asset Store, not those from Unity. I can still download new versions of packages from Unity.