Light Dots in render ?

Light Dots = Firefly

Iray prefers to have light directly hitting surfaces as much as possible... your scene is too dark ( but it's beautiful ).

I recommend to read this article, you will understand better the firefly issue:

Why Is There Noise in My Daz Studio Iray Render and How to Remove It

After all, you also can use the denoiser filter, but eventually your scene will become blurred.

Like Frank21 Said. It's the easiest way without any compromise. Though I find sometimes what frank said isn't enough. You need to change in the same tab Render Quality to 3 or 5 and the Render Converged Ratio to 99%. Do not put 100%. This will typically remove all the "Grain" From images.
The render will take longer, but come out nice.

DD

@amoreto I used an AI program just to show what can be done, but essentially you're right, it just "denoises" the picture. However, it means that if you have an image that's taken forever to render and still has noise, the AI is less destructive as it is applied post render.

I use these settings, works like a charm

Dit a quick example

As said above, you can Up the amount of samples.
In theorie studio renders forever, but there is the factor time.

And there is the hardware...
Used to have a 2 GB GPU and 8GB Ram.
Got myself nes pc not long ago, and man that makees a world of difference
AMD Ryzen 7 5700G
GeForce RTX 3060 12Gb GPU
32GB RAM
M.2 SSD

Pictures that took over two hours render in under 3 minutes.
Had fireflies on old system to, poor thing just coudný handle it