Once I noticed all my non-white colleagues had selected the closest skin tone, I selected the white one.

If I click a black or brown thumbs up in Slack to add my own, a white one is added.

We're a very small team and three of the skin tone choices are unique, so I often know who has reacted from the colour.

Oh yeah, that's totally not awkward. Imagine being the only one of a particular shade of human and constantly seeing your lonely thumbs up next to the the thumbs ups of the rest of the team.