How does Toad predict the winner?

When there are 5 turns left in a game of Mario Party Superstars, Toad predicts which player will win and gives them a bonus. I've seen Toad pick the player in fourth, third, or second place, but never first. The Mario Wiki explains how a winner is chosen for some older Mario Party games, but it doesn't have details for Superstars.

How does Toad predict the winner in Mario Party Superstars? Is he more likely to pick the player in last place?

From what it seems, the process is random number generation. It would make sense since you said you've seen him pick the player in second, third, and fourth. The Mario Wiki says in earlier games that Toad entirely decides through RNG, and I don't doubt it would change in Superstars. The process is not influenced by any player decision whatsoever.

However, it appears that Toad doesn't pick first. One could say that when the game chooses a person to give the advantage, if it returns the player in first, it checks again. Since the first place player already has the lead, it would only make sense not to help them win.

Note: the Mario Wiki won't have as much information on Superstars as it has on the other games since Superstars is relatively new. It's not going to have all of the information.