The tweet below has a video of the glitch being exploited in live action.
Players on Reddit are angry about the glitch being exploited and are calling for players who exploit it to be banned. To win those coins, cheating hiders are placing balloons in those out of bounds areas, and the cheat is being used particularly in New Donk City map of the game. The hider wins coins if the seekers are unable to find the balloons they hid. If they go on a balloon finding streak they win even more coins. If the seeker finds balloons they win coins. If you are unfamiliar with the Balloon World mode, it's sort of like a game of hide and seek from your childhood, only the hider is placing balloons in the worlds of the game and then the seekers must go and find them.
