One thing, before doing a home>settings>system>advanced factory reset, go to >settings>system>power and do a power restart. It won't lose your existing settings. It sometimes fixes things (like the "green screen" problem). I think it has something to do with fast-start being enabled in that same power menu. That option keeps modules in memory. Updates (being as badly done as they are) probably don't manage that very well. May leave things loaded that shouldn't be. Or, corrupt memory. The power menu's restart will start the tv as if fast-start is disabled, and load everything fresh. (My fast-start is disabled. I've read too many things about it causing strange problems.).
It wouldn't hurt to try that. There's also a pinhole hardware reset in the back of the tv. I've read people saying that fixed a problem when the menu factory reset didn't. But, there's a particular way to do it. I've read different ways. I'm not sure if there's really a difference, or just superstition. One way was to unplug the tv. Press the pinhole button & hold it while plugging the tv back in. Continue holding until the front light comes on, or flashes. (Other instructions say to just hold the button 20 seconds, and release when the light blinks. It's unclear if that's with the tv on or off.).
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.
This is exactly what happened to me today. I connected my TV to my wireless for the first time in months. I ran a manual update and when the TV Model 55s245 (7132x) rebooted, the top half of the screen is darker than the bottom with no clear line separating them. With a completely white screen the top half seems to have cloudy grey areas making the screen darker, This IS NOT a hardware issue. Is there any way to roll back this update
Yes, that's the same with my TV. No clear line, but it's quite obvious on a white background.
This issue may be related to a hardware issue. We would recommend reaching out to your TV manufacturer for further assistance regarding what you are experiencing. I'd suggest starting there to see what options or suggestions they can provide. Each Roku TV manufacturer provides direct support for their products running the Roku OS.