Why is my screen gray at startup?

Hi guys,

I am facing an issue lately that I have tried to fix but unfortunately without success.

After I updated the macOS version of my Macbook Pro 2019 15" Touchbar the laptop has a weird issue on start-up. The screen where the Apple logo appears is now gray instead of black. The laptop boots up and works without any issue.

I have tried resetting NVRAM and SMC but it did not fix the issue.

I have tried running the Apple Hardware Test and no issues are being found but the problem can be clearly seen during the test as well (the background is a light shade of gray).

Please let me know your advice for fixing this. Thanks! :)