When on Peaceful mode TNT has the capability of launching the player past sky limit. But on easy, normal, and hard modes TNT isn't able to do much; It can't even send players 50 blocks in one direction.
Regardless of survival and creative, this still happens in both game modes. I have attached the following a world compromised of a TNT cannon setup to prove this bug exists. I've tested TNT multiple times with this cannon and the results are the same no matter how the cannon is configured, even in survival and creative. Peaceful is more powerful than the other 3 modes.
Please look into this, I await your response.
With love and regards.