I am very curious right now. I wanted to render a video about lights and there is that weird glitching heatwave everywhere where it's dark (look at the top around the orange object, dark sides are glitching).
I used default Cycles settings with OpenImageDenoiser and 64 samples. Is it due to denoiser that this is created? Any idea how to get rid of it? I, unfortunately, cannot give the whole file (due to 1GB size) but as I said, all render settings are default expect denoiser.
Every time camera is far away and it is dark these heatwaves are created.
Rendered with AMD Radeon 6700XT GPU
Each frame was rendered with 8 tiles 320x360px (whole res is 1280x720px)