If you have enabled iCloud Photos then none of the photos are backed up including those under Recently Deleted Album.
If you have not enabled iCloud Photos then the Recently Deleted Album is also backed up on iCloud/iTunes. However, the deleted photos and videos will be stored in the Recently Deleted album for 30 days. After 30 days, they will be permanently deleted from iCloud/iPhone.
iCloud backup doesn’t include information that is synced and stored in iCloud, like Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, shared photos, iCloud Photos*, Health data, call history, and files you store in iCloud Drive.
*-If you had turned on iCloud Photos, your content is automatically stored in iCloud.
- WARNING: If you delete the iCloud backup for your current iOS or iPadOS device, iCloud stops automatically backing up the device.