PUBG's C4 has been a rather fun addition, but like every item in the game, it can be broken in certain scenarios. PUBG has made the C4 do damage to allies and enemy players alike in a rather wide radius. And to make matters worse, it does damage through buildings.
Throughout most of the game, it's a great addition and allows players to enjoy a well-made explosive. It targets vehicles well and is fun to use in building fights, but it's terrible for end-game scenarios.
Redditor HEEROMYMAN showed how powerful the explosive can be in the end-game. During the last circle, two players were up against one enemy player and decided to try to end it with a favorable C4 instead of a heal off. They go to throw the C4 over the ledge, but instead land it right in front of them. They run as far as they can and start to heal. The C4 explodes, knocking one of the allies down, but luckily, it knocks the last enemy player as well, giving them the win.
As you can see, the C4's range is broken in the final circles, but compared to heal offs, I would rather prefer the boom.