You specifically configured Google Drive for Desktop to "Stream files" instead of "Mirror files," expecting your 256GB Windows C: SSD to stay clean. Yet, after opening a few video projects, Windows triggers a red warning: "Low Disk Space on Local Disk (C:)". Opening a disk visualizer reveals that a hidden folder named DriveFS inside %LocalAppData%\Google\ has secretly consumed 80GB of space.
Google Drive for Desktop caches every streamed file on your primary operating system drive by default. To safely relocate this cache to a secondary SSD or external drive: open Google Drive Preferences > Gear Icon (Settings) > scroll down to "Local cached files directory" > click Change > select a folder on your secondary D:\GoogleDriveCache drive > click Restart now.