Can you help me?

[TheReal MrBitcoin]

I have been using Debian 11 bullseye since September 2021. At first
everything was great. Than a week ago my screen after start up turning very
dark & the back light screen is very dim.
I would like to know how to make the screen bright again.
I have spent hours on YouTube & doing Google searches to try to solve this
with zero luck.
Thanks