Hi tarotocol,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
Thank you for reaching out to Microsoft customer support. I'm sorry to hear that you're experiencing issues with your Surface Pro 7's screen brightness fluctuating.
To troubleshoot this issue, please try the following steps:
- Force a shutdown and restart your Surface: Force a shutdown and restart your Surface - Microsoft Support
- Run the Surface Diagnostic Toolkit: Fix common Surface problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support
- Disable adaptive brightness: Content adaptive brightness control in Windows - Microsoft Support
- Manually update Surface drivers and firmware: Download drivers and firmware for Surface - Microsoft Support
- Verify in UEFI, if the issue persists in UEFI then we know it is a hardware issue. How to use Surface UEFI - Microsoft Support If it doesn't appear in UEFI and the above methods don't work, try resetting your Surface.
- Reset using the most appropriate choice. If you've tried basic troubleshooting options, you may need to restore or reset your Surface. If the issue occurs after a reset, then the root cause is very likely hardware related. Restore or reset Surface for Windows - Microsoft Support
- If the issue persists after the reset and is in UEFI, refer to this link for repair and service of your Surface. How to get service or repair for Surface - Microsoft Support
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn. W - MSFT | Microsoft Community Support Specialist