Lockscreen turns black

This morning by iphone lockscreen turned black. I don't see a reason for this. I do have bedtime features with a certain time window; I've been using this for years. The bedtime usually does not turn the screen black, it keeps the picture but dims it. It is outside the bedtime window and the lockscreen is completely pitch black. I reset the phone, the lockscreen picture came back normal, then couple minutes later, it's black again. There is likely a bug in the OS. I have the iPhone 13 mini with iOS 16.2. I don't know how to bring my original lockscreen picture. The settings shows that it should be my picture.