Using this system is totally fine, yet it should be clear to everyone, and based on an “official” statement by contest organiser(s), rather than speculation.
The fun part is that I even quoted the OP looking for this kind of stuff, but I missed that “hidden” code.
Yes, I think you are right. This should be amended asap and made clear to everyone.
Based on how people are voting and how the pizzas are presented (in sequential order from 1, 2, 3…), someone can easily miss this point. Voting in order matters, and when scrolling from 1 to 112, you will automatically choose 5 pizzas in ascending order.
I agree that this needs to be highlighted more prominently, or something like this might help.
1st:__, 2nd:__, 3rd:__, 4th:__, 5th:__
Or
First:__, Second:__, Third:__, Forth:__, Fifth:__
Or
First Place:__, Second Place:__, Third Place:__, Forth Place:__, Fifth Place:__