All monitors suddenly are black?

Hello seamusfurr0,

Thank you for using Apple Support Communities and for sharing these details with us. Sounds like you've done a great job in troubleshooting this issue with your external displays. From here, we'd like to recommend some more steps you can try to help troubleshoot this issue. Let's check out this resource here: If your external display is dark or low resolution - Apple Support

This resource does have steps for when your display is blank. It does suggest to test different cables. You did mention that your cables are fine. If you test a different cable, does this specific issue continue to occur? You also mentioned that you're fully updated. To further isolate a possible software related issue, try starting up in safe mode. This step can help isolate possible software related issues: How to use safe mode on your Mac - Apple Support

Apple silicon

1.) Shut down your Mac.

2.) Turn on your Mac and continue to press and hold the power button until you see the startup options window.

3.) Select your startup disk, then press and hold the Shift key while clicking “Continue in Safe Mode.”

4.) Log in to your Mac. You might be asked to log in again.

Depending on your results, follow the steps under “If the issue continues in safe mode” or “If the issue doesn't continue in safe mode”.

We hope these steps help you out. Thank you for using Apple Support Communities. Cheers.