Why are you still rolling out insider updates that are giving people black screens that...

They haven't been in Insider preview that long, so may not be in any public update soon. That is the most information that anyone can give. I can say Alexa control is still limited access and not rolled out to many in the Insider Program.

I'm see a black screen after finishing the update that roll out yesterday August 22 2021, I don't see my dashboard in my xbox, I can see that it logs in but the only I see is a black screen but no dashboard.

It's still rolling out so you'll get it at some point. When they roll out updates there's no way to know why someone else got it before you or when exactly you will get it.

Updates are typically rolled out in waves so they don't hit everyone at once and cause server issues. So it's not unusual to have someone else close by get an update and you haven't, Insider or not. If you still have the Insider App installed try using
that to see if it still shows your console as being enrolled.

Hello there,

I have an Xbox One X and this issue started occuring after an insider update so I presume you are also part of the insider program. Once I saw the black screen on my tv, my first instinct was to turn off or restart console but instead I ended up just pressing a bunch of the face buttons until the black screen went away. This happened to me twice afterwards the insider team released another update to fix this. Once you get past the screen, update your console and the black screen should go away.