I had an Echo Spot in my bedroom, and had created a two-part "goodnight" routine: it turned off lights in the bedroom, then a custom action turned off the Echo's display ("turn off your display"). Worked just fine.
Some time ago I bought an Echo Show 8. That replaced a Show 5 which I then put in place of the Spot in the bedroom (the Spot was put elsewhere).
The Goodnight routine works, except that just about 1 minute later, the Show 5's display turns itself back on. There is no indication why: it's not accompanied by a sound and the display has no message (just the standard home screen). But if I say "Alexa, goodnight" a second time, the display turns off and doesn't turn back on until the morning wakeup routine.
What's going on?