Black square on left side of the screen while playing

To solve the issue, you have to unchecked the option flash reflex in performance monitoring. And It's done

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today despite this THEROBERTO2512

Let’s try to isolate the issue a bit more, for this please try:

A. Double check if everything is up to date in your system

Open Settings, click Update and Security and then Windows Update
Click Check for Updates

Click the Download and Install Now option, if available (Install optional updates as well)

Then, check the Microsoft Store for any updates on the Xbox apps and its services and update everything too. (Click on get updates)

B. Open task manager > select the startup tab > disable all the programs listed there temporarily
Restart the PC and try again

C. Do a clean boot in your PC and try again
https://support.microsoft.com/en-us/topic/how-t...

D. Create a new local administrator user in your PC and try from there
https://support.microsoft.com/en-us/windows/cre...

Where is this located?

Open the GeForce Experience Overlay, then go to Settings > Performance Monitoring and uncheck the option "flash Reflex"

It's the controller sync button like the one that was on 360, the black square button beside the usb ports, so if you wanted to connect a new controller you would press that and at the same time the button on the left side of the Xbox guide button, hope
this helps

Is it just a black screen that you get? Not sure if it's the same issue, but I get this sometimes as well. The way that I get around it is that it will still let me press the Home button on the controller, which will bring up the side bar menu on the left
side of the screen, over the black screen. I'll then select Home from the menu, and it will freshly load the Home screen on the Xbox and there is no more black screen. Hopefully that works for you as well.