Yes, the Redmi Note 14 Pro+ 5G supports the background app lock.
For your reference, here is more information about the background app lock:
1. Background app lock is a feature designed to prevent certain apps from being cleared or closed when you use the one-tap clear all background apps function (often through the task manager or recent apps screen);
2. This feature helps ensure that important apps (such as messaging apps, social apps, or health apps) remain running in the background without being mistakenly or intentionally closed;
3. Ensuring key apps stay open in the background allows them to continue working, providing stable services like notifications, health monitoring, and more;
4. To enable background app lock: Tap [Security] >> tap [Settings] in the upper right corner >> tap [Boost speed] >> tap [Lock apps] >> turn On/Off the APP you choose.