A month after Apple released version 13.6 update for iOS and iPadOS comes version 13.6.1, which fixes some issues on the platforms, including a green tint that's been appearing on some iPhone 11 devices. The cause is reportedly a thermal management issue and triggered by an earlier update (likely iOS 13.4). The update resolves a problem that disabled Exposure Notifications for some users. It also got rid of the issue where unneeded system data files weren't automatically deleted when available storage is low.
The update size is 110MB, and it should be available through Settings > General > Software Update, or a notification for the update has been sent your way. This iOS 13 update might be the last one we'll see as Apple is expected to drop iOS 14 next month.
Source: Digital Trends + GSMArena