my 13 Pro Max having two horizontal lines when locking after the iOS 18 update

Device: iPhone 13 Pro Max

iOS Version: iOS 18.3.1 (also noticed in iOS 18.3)

Issue Type: Display glitch (likely software-related)

Description:

After updating to iOS 18, I noticed a display glitch where thin horizontal white lines (around 3mm wide) appear for a split second when locking the screen. The lines are not always in the same position but usually appear in the middle or bottom half of the screen.

Key Observations:

• The display works perfectly fine otherwise (no issues in games, videos, or daily use).

• The glitch is only visible for milliseconds while locking (not during unlock or normal use).

• Many other iPhone 13 Pro Max users have reported the same issue on Reddit and Apple Community after iOS 18 updates.

• Reducing White Point in Accessibility settings reduces the flashing intensity.

• A full device reset didn’t resolve the issue.

What I Tried:

✅ Resetting all settings – Issue persists.

✅ Updating to iOS 18.3.1 – No change.

✅ Testing at different refresh rates (60Hz & 120Hz) – Still happens.

✅ Powering off and on – Sometimes no flashing, but appears again later.