How to disable change Wallpaper from Lock Screen

Following this thread is like being in a support group. Apple will never fix it, no matter how many times we use "Product Feedback", but every few weeks someone else complains and we all know at least we're not alone.

I suspect that an "intended feature" that was poorly evaluated and possibly not tested from the user interface standpoint will be way too complicated to ever fix.

As you have rightly noticed, there is no function that can deactivate this function when the iPhone is unlocked. I don't experience it as a problem myself, but I have read several people who do.

You can always send a Feature Request feedback to Apple here:

Product Feedback - Apple

If you don't have a Passcode set on your iPhone, then the scenario you mention is possible.

But it is not possible to start Lockscreen Customizing when the phone is locked, but if you use FaceID, your iPhone will automatically unlock, almost at the same moment as you look at the screen.

To avoid this, you can disable Raise to Wake. This function turns on the screen of your iPhone the moment you lift it into your pocket. You can do this here: Settings → Display & Brightness → disable Raise To Wake.

You can also disable Tap To Wake. With this feature disabled, your iPhone screen will not turn on when you tap the screen when it is off. In this way, the screen MUST be activated with a press of the Side Button.

You can disable Tap To Wake here:

Settings → Accessibility → Touch → disable Tap To Wake.

EDIT: Arhh you didn't tell me first that you were using an Apple Watch.

You can also deactivate this function, find more information here:

Unlock your iPhone with Apple Watch - Apple Support

This drives me CRAZY! Tell me Apple—How can I **** can this feature! I like my phone just the way it’s been for ten years!