Those posts are either old ones from when RDNA 3 first launched, or coming from people who don't know what they're talking about.
The 7800 XT is a huge jump from my 6750 XT, and since AMD solved the idle power problem a couple of driver versions ago, I couldn't be happier with it.
That's the thing. Different games use different parts of the GPU differently, and since you're power limited basically all the time, the power allocation allows for different clock speeds under different loads.
If you max out the power slider, you'll see much more consistent clocks across various games.