I guess my post above was waaaaay too long to be parse-able, which makes sense.
Things are dark because:
1. I was doing the lighting and color grading on an HDR TV. Most monitors, even really nice ones, are not HDR. You get a much wider color range on that, and so I could see things on it that I can't even on my very nice laptop screen. This is basically what happens when you show an HDR image on an LDR display.
2. I'm now re-grading things on my monitor. This makes things look slightly washed out on my HDR display, but still visible, and it looks vastly better on every other screen in general. So it should be the best of all the various worlds.
3. But even beyond that, it got extra dark at some point because of some changes in the engine rendering pipeline that made shadow calculations different. So things got darker without me noticing it, and so even on the HDR display it's too dark now, to an obnoxious degree. I spend most of my time focused on the icons and it slipped past me because I didn't expect that things would change like that.
4. TLDR of the TLDR, I agree with you guys and this was a couple of levels of unintentional.