Mafia 44. Time of Troubles

Explain to those who don't like it, what is the purpose of these chickens? Because sometimes I get a rotten broiler, sometimes a happy one, but nothing changes.
Is it just for show?

Yes, it's for show. They usually show the attitude of the group towards a person (well, unless there's a situation where someone deliberately upvotes or downvotes). Besides, it is assumed that increasing morale should be pleasant for a person.

And why leave an extra one? Does it replace the GM's clue, or will there really be two clues pointing to the Mafia? Although I like the idea anyway.

The idea isn't mine; it's absolutely classic. The Mafia will be given two clues (one from themselves and one from the GM). The point is that the planted clue can be open to double interpretation: it will point to the Mafia, but (in another interpretation) also to some other player. Thus, the Mafia can introduce additional confusion into the game, which is beneficial. Although it should be noted that planted clues are rarely used.

The information is 100% accurate!
But does it work, or is it just for decoration?

It so happens that I am against unjustified hints in life. So I will strictly monitor compliance with this rule. Nevertheless, statements like "based on these logical considerations, it turns out that I have a chance of being such and such a role" are allowed, although one must also be careful here and not cross the line.