If the option to downvote songs is grayed out, it means you've reached the daily limit for downvoting tracks.
The good news is that the downvote lock is not permanent. You can unlock the downvote option by simply upvoting other songs in the music Queue.
Why is there a limit on downvoting?
Music should be fun! And we want to incentivize positive interactions among our DJs.
DJ users are encouraged to engage with other DJ song picks but engagement does not mean downvoting all other songs in the Queue so that yours plays first. A Rockbot DJ should be able to express dislike for a piece of content, but they shouldn’t have the ability to dominate the playlist to the detriment of the venue staff and the other DJs on deck.