In prior versions of 7 Days to Die, the blood moon horde pretty much lasted from 22:00 to 4:00, and the horde promptly stopped spawning at that point. Now in Alpha 17.4, I've started a new random gen single player game, and had my 7th day horde. At around 1:20am, no more zombies spawned. I know there's a limit to the number that can spawn at once, and I've seen them start wandering before, so I jumped down and ran around looking, and couldn't find a single one. I did notice, however, that the color of the moon was no longer red. I've not seen this in any patch notes that I can recall, but does the color of the moon indicate when the blood moon horde is over?
As you can see in my screenshot, the sky seems the normal horde-night orange/red color, but the moon is grey. Could this be the indicator?