Delay in lock screen

Hi Sajakankouni,

Thanks for posting in Apple Support Communities. It sounds like you've tried some great troubleshooting so far.

Next, since underlying issues such as battery health, apps, etc. can impact performance, try the guidance in About iOS or iPadOS performance on your iPhone, iPad, or iPod touch to help isolate and possibly resolve this. All sections of that article are important to try but we wanted to point out a couple that may be particularly helpful. Battery health is directly related to overall performance.

"Leave Low Power Mode off when you don't need it

Low Power Mode is an iPhone and iPad feature that extends battery life by reducing the amount of power that your device uses. In Low Power Mode, some features are turned off and some tasks might take longer to complete. If your battery icon is yellow, that means Low Power Mode is on. 

Consider leaving Low Power Mode off if you need your iPhone or iPad to function without low-power restrictions. You can turn Low Power Mode on or off in Settings > Battery.

Get more information about Low Power Mode."

"Look at your battery health

All rechargeable batteries are consumable components that become less effective as they chemically age. Over time, the rechargeable batteries in all iPhone models will diminish in their capacity and peak performance and will eventually need to be replaced. iOS can show show battery health and recommend if an iPhone battery needs to be replaced. Go to Settings > Battery and tap Battery Health. Battery Health is available only on iPhone.

Check your iPhone battery."

Best of luck.