Pale blue/teal on a mid-gray background is nearly invisible -- even without glasses.
I listed my discusssions and initially thought you could only down vote.
On your own suggestion, you can only downvote. You've automatically upvoted when you made the suggestion. If you decide, later, that it was not a great idea or not needed, then you can downvote it.
When I look at your suggestion above, I see an up and a down arrow - both the same color. I can't downvote your suggestion; only a mod can do that.
You're showing a screen shot of a suggestion you already upvoted. It's initially black, but changes to be much lighter once you've upvoted. You certainly have a good point that the color choice for the upvote arrow on an upvoted item has very poor contrast with the background. But that isn't how it is shown initially to most people.
It would be nice to be able to actually see the arrow in case I were to want to down vote something.
I do appreciate you letting me know that everyone else sees an arrow and it really is just me that can't see it.