Placeholder colour for floating labels

[lonix1]

Discussed in https://github.com/orgs/twbs/discussions/39394

^{Originally posted by lonix1 November 12, 2023}
For floating labels: in the non-floating position it is dark, and in the floating position it is light.

But a placeholder is typically light to show that it's not real text.

I was surprised that in the non-floating state it is a dark colour. I thought it must be a mistake on my side - but when I checked the docs I found that it is the same (dark).