TV stuck on pink static when connected to Apple TV, goes away with resolution cycling + waiting for screensaver

Hi! A couple weeks ago, I started having issues with the connection between my Apple TV and my TV (2014 LG 79" UHD TV). My setup is exactly the same as it's been for a few years, and it always worked perfectly, so there's no clear trigger for the start of these issues.

Whenever I turn my TV on and it's connected to the ATV, I get a pink static screen, I can hear audio, but can't see anything but static. I can get the TV to work by prompting resolution cycling from the ATV remote (holding Menu + Volume Down button for 6sec) and then waiting for the ATV screen saver to come up. When I do this, I keep seeing the pink static screen, the screen flashes black for a second or 2 a couple of times (I assume in response to the resolution changing from the cycling) but keeps going back to pink static; it stays this way until I get my screensaver, which I can see perfectly, and everything works fine after that. The TV then works fine until the next time that it's turned on again from being off.

Things I've tried so far, for diagnostic purposes and/or in attempts to fix (none worked):

1. Unplugged both the TV and ATV from the wall, and left them unplugged overnight
2. Factory reset both the TV and the ATV
3. Connected the ATV to a different TV (it works fine on the other TV)
4. Connected a different ATV, same model, to the TV where I have the issue (same issue occured)
5. Tested other inputs (BluRay player and video content from external hard drive) on the same TV - everything works fine except for the ATV
6. Used Reset Video Settings feature on the ATV - can only prompt this once the connection is working again after the static, so it makes no difference in the current session, and the same issue occurs again the next time I turn the TV and ATV on
7. Manually changed the resolution on the ATV to one of the settings that works after I've gotten out of the pink static phase - I don't know if the TV turns on with the same resolution, because I get the pink static screen the next time I turn it on and have to use resolution cycling to get back to being able to see the ATV, so either the resolution defaults back to a problematic setting every time it turns off, or leaving the ATV set to that resolution doesn't fix the issue.

I am convinced at this point that it is a software issue, not a hardware fault, because once I get out of the initial pink static phase (lasts anywhere from 3 to 15min) each time I turn on the TV, everything then works just fine, and all other inputs to the TV work fine with zero issues.

Has anyone else experienced this and found a cause and/or fix for it? Does anyone have any suggestions for other things I can try? Any help would be appreciated!