PSA: update the tcon firmware if screen starts dimming weirdly.

Tested on a Roku TLC 55" TV Model 55S455 Software: 12.5.0 build 4176-CG

I noticed that the TV had updated itself 10/31/2023 and shortly afterwards the left half of the screen suddenly dimmed more than the rest of the display. It didn't seem like a hardware issue because it went away when restarting the TV or toggling the "turn off display" mode.

I seemed to have fixed it by poking around and going into the "TV Secret Screen" menu and applying "Upgrade Tcon PM intergrated with Gamma". After which the issue hasn't seemed to come back for me.

To see if your device has this setting you'll need to enter the "TV Secret Screen" menu with a series of button presses on the Roku TV remote that came with your TV. Starting at the main home screen: press home button 5 times, rewind button, down button, fast forward button, down button, and lastly rewind button again.

I hope this helps someone else.