Disk standby button - disappeared

[Jopp-gh]

I know there was a standby button in the shutdown dialog, but now I count only 3 buttons (from L to R):

1. Cancel
2. Restart
3. Shutdown

The standby button is missing now (To pause the HDD and the monitor)

Is there some preference to reactivate this button? 😳
Where to find this button now?

[Jopp-gh]

Oh, the standby button is back in the shutdown dialog, with the other buttons as well.
Strange...

edit
Just keeping this question open bc I'm curious to know why a button can disappear.