Temporary Dimming Spots or Lines on My LG C3 OLED Screen

I have an LG C3 OLED TV, and I’ve noticed an issue where certain small areas of the screen temporarily become dimmer than the rest. This usually happens when I pause a game and the screen goes dark. The dim spot can appear in different locations—sometimes at the top, sometimes at the bottom, and occasionally as a wide horizontal line.

The dimming lasts for a few seconds before returning to normal, and I only notice it because of the sudden brightness change. It does not seem to affect the entire screen, just certain areas.

Does anyone have the same problem?

Here's a short video explaining what I mean (there's a slightly thick horizontal line at the top of the screen that's not noticeable until it immediately returns to normal brightness) https://youtu.be/aeVpN7oz1BI?si=eW6541q3YRp_6uSR