Same problem, I’ve got a RTX 5070 too
Exactly the same here… But I know waht the cause is.
The option in “general” section of settings which says “Lower FPS when control is disconnected” (or something like that, my game is in spanish). If you disable that, it stops happening. So the problem is clearly related with that option.
Happens to me too. At first I thought it only was when I enabled some resource packs or vibrant visuals, but it turns out that it happens like you say, when you’re not looking directly at the source.
In case it's useful, I’m on bedrock 1.21.93 and I have a RTX 5070 with a Ryzen 5 7600 and 32 GB of RAM.