When selecting a powerup (not ability) in Temple Run 2 you have the option of making it "Gem powered". For example, here is the Coin Bonus one:
It's easy enough to infer that this gives you 50 gems normally, and 100 when you spend a gem on it.
However, what happens when you add one, two, three, or more gems?
Here's what I tried. This is what the screen looks like when you add one gem and this is what happens when you add two. Adding more simply fills the bar without text changes. After powering with two gems, here is what happens before and after using the powerup in-game: even if I spent two gems, I only got 100 coins. This spent both gems.
What is the point, if any, of upgrading past one gem? Is this specific to the Coin Bonus powerup? Or is this just a glitch and it should be adding 50/100 coins per gem?