We can not change the voting buttons of the photo competition, as we use normal question and answers pages.

Unless we want to ask the staff at Stack Exchange to design new pages for us, (which is something I do not expect to happen at all.)

I am going to ask people not to downvote, but that is something people are free to do.

@gparyani, pinging mods by name is much more efficient than a random call here. I am the site several times each day and will see pings. I do not come into the chatroom each time, nor do the other mods.

@Willeke Thanks for letting me know. In many of the other rooms I participate in, pinging mods is often frowned upon, so thanks for letting me know otherwise.

@Willeke Viewing vote counts is possible, so it's possible for only upvotes to be considered.

I did some further research and it looks like the main reason is that people who were submitting photos were downvoting others' submissions to give theirs an edge.

@gparyani, as nobody can see who cast a vote, (also not the mods,) it is impossible to tell why the down votes are cast, unless someone declares it. As Sue did, who had not really read the whole of the question and was sure some of the photos were against the rules.

She has reverted those votes, by the way (according again to her own words.)