Why does the font color of my lock screen depth of field fade?

Hi 韩256,

Thank you for participating in the Apple Support Communities. If you are having issues with your lock screen, here are a few steps that may be useful:

1. Restart your iPhone to see if the issue persists: Restart your iPhone - Apple Support

2. Update your iPhone to rule out the older software: Update your iPhone or iPad - Apple Support

3. Try the steps here to see if they help: Change your iPhone Lock Screen - Apple Support

4. If you need further support, reach out to Apple Support here: Get Support

Have a great day.