how do i keep the Always on Display on all the time? even when its charging on my nightstand at nights

Always On will automatically switch off after some time if you do not use it, for example when it is left in your nightstand at night. Unfortunately, it is not possible to keep the screen on without deactivating Auto Lock. The problem with Auto Lock set to Never, the Always On display does not start and your iPhone is not locked while you sleep. Always on only activates when the device is locked.

You can disable Auto-Lock here:

Settings → Screen & Brightness → Auto Lock → Never

You can read more about the iPhone 14 Pro's always on function here:

Use Always-On display with your iPhone 14 Pro or iPhone 14 Pro Max - Apple Support

I have this same issue. I want the phone to keep showing at least the time while plugged into its charger on my nightstand. Tried an app that claimed to do that and got spammed with ads. Very disappointed with Apple's claim of an "Always on display" that simply is not what it's advertised to be.