Hi Julian,
Thank you for reaching out to Microsoft Community, Regarding on you issue/concern "Surface Laptop 7 Screen Backlight Not Working Correctly After Latest Hardware Update". If you suspect you got the July 10 update and not the August 7 fix, you can manually install the latest firmware. Visit the Surface Drivers & Firmware page https://support.microsoft.com/en-us/surface/download-drivers-and-firmware-for-surface-09bb2e09-2a4b-cb69-0951-078a7739e120 then select your device: Surface Laptop 7th Edition, Download the .msi file that matches your Windows build (e.g., Win11_22621_xx.msi).
Run the installer and restart your device.
Please let me know if it works. I await your response.
Warm regards,
JayMark.D | Microsoft Community Support Specialist