Hmm, now I'm remembering something.

While you can't have a light that affects only chosen items in the scene, you can go into Materials (Advanced tab) for the light and set Diffuse to black and Specular to white. So do that on a spotlight you're pointing at the hair and see if that helps. Adjust intensity and Point At rate to suit.

Of course, this isn't a way to "get things to look like they used to." But it should get the hair brighter and shinier relative to the rest of the scene without blowing things out.

Note: I've never used specular-only lighting myself (I guess I would for a particular effect, but usually I'm after realism), so can't comment on its effects.

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Hardware: AMD Ryzen 9 3900X/MSI MAG570 Tomahawk X570/Zotac Geforce GTX 1650 Super 4GB/32GB OLOy RAM

Software: Windows 10 Professional/Poser Pro 11/Photoshop/Postworkshop 3