Based on screenshots that have been shared out on the Discord and the preview images on the Play Store listing, that appears to be the case. Upvoted posts are still marked orange. Whether that will change at some point after release, I'm not sure, but I'm fine with it either way.

I think the colors are arbitrary, though. Jerboa, for example, just sets the colors to match my Material You theme, so my upvotes are brown and my downvotes are burgundy.