Hi there, Sako177.
To clarify, are you showing the screenshots to show the difference in color in Safari versus the color in Settings? If yes, are you noticing this in any other apps?
Do you continue to notice this if you toggle Dark mode off and on again in Settings > Display & Brightness? We're asking this as toggling the setting might help reset it.
Also, if you haven't already, you can see if restarting your iPhone might help, as it refreshes the iOS and can sometimes help resolve unexpected issues:
"How to restart your iPhone SE (2nd or 3rd generation), 8, 7, or 6
- Press and hold the side button until the power-off slider appears.
- Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
- To turn your device back on, press and hold the side button until you see the Apple logo."
Those steps, and more, can be found here: Restart your iPhone - Apple Support
Take care!