Windows saves a copy of the previous installation files in case you don’t like May 2020 Update and you want to rollback to the previous version of the OS. In this guide, we’ll walk you through the steps to delete the previous install files of Windows 10 saved on your system drive and reclaim original storage space. You can also open Temporary files page in Storage settings to reclaim space after updating Windows 10. The November 2019 Update is still rolling out to consumers but you can reclaim space using Storage Sense feature.
Source: https://www.bleepingcomputer.com/news/microsoft/how-to-free-up-space-after-windows-10-may-2020-update/