LinkedIn’s job screen in the app is a good example of this different presentation.

I’ve noticed a certain AI recruitment company gets “highlighted” (darkened white background of the screen, but their logo is pure white and REALLY stands out), but when I screenshot it, it reverts to normal, like there’s no blatant special advertising.

Different underlying mechanism. The LinkedIn one (and almost all ads on Instagram/Facebook these days) use a gain map to increase the brightness of the image. Here's a site demoing the tasteful application of this [0], you can see the difference viewing it live versus taking a screenshot of the result.

[0]: https://gregbenzphotography.com/hdr-gain-map-gallery/