Burn marks on the render and strange lines, shadow composite not working

Support Lighting and Rendering
1

Can someone help me? i have been doing these donuts for today, my fisrt problem was the shadows where very grainy but i fixed it with https://gyazo.com/b9d12de8a32b27197d1d887c1615a83b
compositing and now when i made some sprinklers on the donuts it just became like this

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untitled1920×1080 504 KB
and i have no idea on how to fix it

2

Looks like denoising artifacts, try to disable denoising. But can you upload somewhere your .blend file?
Edit:Try to increase samples number in render settings. With low samples denoiser can do such artifacts.

3

here, the blend file.

4

I downloaded your file, then rendered with no changes, except i’m rendered on CPU:

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untitled1920×1080 388 KB

So maybe in because you GPU. I dont know problem else it can be. Sorry.

5

i fixed it, i had some setting being… idk strange and i reseted my settings to factory and now it works