🩹 Fix M80, 1s delay (#23455)

Marlin/src/feature/power.cpp

   }
 
   void Power::checkAutoPowerOff() {
+    if (TERN1(POWER_OFF_TIMER, !power_off_time) && TERN1(POWER_OFF_WAIT_FOR_COOLDOWN, !power_off_on_cooldown)) return;
     if (TERN0(POWER_OFF_WAIT_FOR_COOLDOWN, power_off_on_cooldown && is_cooling_needed())) return;
     if (TERN0(POWER_OFF_TIMER, power_off_time && PENDING(millis(), power_off_time))) return;
     power_off();

Marlin/src/gcode/control/M80_M81.cpp

     ZERO(thermalManager.saved_fan_speed);
   #endif
 
+  safe_delay(1000); // Wait 1 second before switching off
+
   LCD_MESSAGE_F(MACHINE_NAME " " STR_OFF ".");
 
   bool delayed_power_off = false;
 
   #if ENABLED(POWER_OFF_TIMER)
     if (parser.seenval('D')) {
-      delayed_power_off = true;
-      powerManager.setPowerOffTimer(SEC_TO_MS(parser.value_ushort()));
+      uint16_t delay = parser.value_ushort();
+      if (delay > 1) { // skip already observed 1s delay
+        delayed_power_off = true;
+        powerManager.setPowerOffTimer(SEC_TO_MS(delay - 1));
+      }
     }
   #endif
 
 
   if (delayed_power_off) return;
 
-  safe_delay(1000); // Wait 1 second before switching off
-
   #if HAS_SUICIDE
     suicide();
   #elif ENABLED(PSU_CONTROL)