If you're displaying a static edge browser for several minutes, it's normal that the TV dims to prevent burn in. If you insist to disable this type of protection, you can try the Control Control app and enable expert settings to disable GSR and TPC but it can void your warranty. u/frtls wrote a guide about it: https://github.com/fritolays/notes/tree/main/lg_oled

This is from the c3, but it might be a similar situation for the c4. I don't yet have one of these TVs, so I can't speak from my own experience.

from https://www.rtings.com/tv/reviews/lg/c3-oled

Setting Peak Brightness to 'Off', which bypasses the ABL [Automatic Brightness Limiting], reduces the peak brightness to about 200 cd/m², which is a much more radical reduction than what we saw on the LG C2. Note that setting the input to Game Mode or PC Mode*, or setting the* 4:4:4 Pass Through option to 'On' also locks the Peak Brightness option to 'Off'.

Wait, is that for SDR only? Would be pretty shitty if Game Mode's HDR only got to 200 nits.

From what I know, this dimming behavior is a feature to prevent burn-in on OLED displays. If a static image is displayed for several seconds, the display might detect this and automatically dim the brightness to protect the screen.Unfortunately, I don't think there's a way to directly turn off this feature, as it’s designed to prevent potential long-term damage to your OLED panel. Keeping the brightness fixed might cause harm over time. Regarding Dolby Vision and Atmos, I'm not an expert, but there are many Dolby experts in the official LG OLED Discord. If you're interested, I can send you the link to join and get more detailed advice

can I get an invite? I have a similar problem where I'm playing games like Horizon Forbidden West, Helldivers 2 and it auto dims when it's daytime etc..