To find "hidden" storage used by connected apps, go to Settings > Manage Apps on the Google Drive web portal . How-To Basics
You can instantly check your storage usage by clicking "Storage" on the left-hand menu in Drive; this automatically sorts your files from largest to smallest. 29-jan - Google Drive
Reports circulated regarding WhatsApp building its own encrypted cloud as an alternative to relying on Google Drive storage limits for backups. Essential Storage & Management Guides To find "hidden" storage used by connected apps,
For those using the desktop version, you can install Drive for desktop to open files directly in your computer's native applications. 29-jan - Google Drive