Small purple line appears under 5G on iPhone lock screen

Please see the pic below

The bar you are referring to in the top right-hand corner of the iPhone, below the status symbols, is called the "Control Center Indicator" or "Control Center Grabber." It is a small horizontal bar that provides a visual cue for users to access the Control Center by swiping down from the top-right corner of the screen. When you swipe down from that area, the Control Center is revealed, allowing you to access various settings and shortcuts.

That small horizontal line below the cellular/wireless/battery indicator on your iPhone serves two purposes:

1. Control Center Handle: It acts as a visual indicator for where you can swipe up to access the iPhone's Control Center. Think of it as a handle or grab point. This functionality applies only to the Lock Screen; once you unlock your iPhone, the line disappears.

2. Privacy Feature: The presence of the line also indicates that the Control Center can be accessed from the Lock Screen. This might be a security concern for some users, as anyone could potentially access features like Airplane Mode, Wi-Fi toggle, or even adjust brightness without needing to unlock the phone.

If you're not comfortable with anyone accessing the Control Center from the Lock Screen, you can disable it in the Settings app. Here's how:

1. Go to Settings on your iPhone.
2. Scroll down and tap Face ID and Passcode
3. Enter Passcode
4. Under the ALLOW Access WHEN LOCKED section --> toggle off the switch for Control Center.

Now, the line and the ability to access Control Center from the Lock Screen will be gone.

This may help --> Learn the meaning of iPhone status icons - Apple Support (IN)