Applied denoiser as well, rendering in cycles on GTX1050Ti
Also why is there that weird noise just behing the rocks, like smudged kind of thing?
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I am not sure why this is happening, but I have narrowed it down to your light with some basic trouble shooting.
It happens with only a lamp and the floor thus only place the problem can be. Applied the scale to the light and lines gone.
Check scaling on all your lights... and the rest of your items.