Standby clock display not staying OFF

15ProMax. Charging sideways on stand, Standby on, orange night setting on, Always On on, Low Power Mode Off, Motion to Awake on, dim set to automatic. Going to sleep everything works as it should. Screen turns off after a minute or so, turns on with movement (no touch required), and turns off again. Middle of the night, screen dark, turns on with movement, goes dark after a bit as usual. In very early morning, room still dark as ever, screen display is now always on and doesn't turn off automatically. (By then phone is back to 80% charge as configured - not sure if this is a factor.)

I would like the screen to turn on briefly when motion is detected and remain off otherwise, as it is when I go to bed. Is this a bug or a feature?