Dark To Light Grading with HSL Secondary

Neil explained it perfectly.
The more you lighten the more noise you will get.
One great solution is a neat plugin called "Neat Video Denoiser" (pun intended) It's not very expensive but it is very heavy on the system. so it depends on the duration of the clip, if there is hard movement, etc. Either you work with Lumetri and Neat, or you go the compositing route with AE, which open doors to many possibilities and workflows

Taking that to light pink ... woa, yea, that's a change.

You might try getting a mask on it, and using "replace color" in Premiere. Possibly maybe it might work ... ish.

Or you might need to go to the similar tools in Ae, which are far more powerful and capable. And for that, ask on the Ae forum.

Neil

Going from a dark blue to a light pink is a massive correction. Think about simply the dark to light ... in that dark blue, unless you've got 422 media that's intraframe at least ... 444 better ... but very unlikely ... you've got significant digital noise but you won't see it.

Simply lighten that dramatically, and now you'll see more of it.

Now force a major hue shift, and the hue range of the noise is going to become very prominent.

Replacing that rather than forcing the current pixels to change would be the far better alternative, and yes, probably a job in AfterEffects by someone who knows how to bend Ae around a bit.

Neil

Can you post the image? That's a pretty intense color correction, probably more than a simple color correction can handle. You could try adjusting the noise and blur settings, but likely, you'll wanna mask out that layer if it's simple enough in Premiere, or if more complex movement then in AE.