I’m not certain how you calculated amps but it is incorrect. Higher voltage applied to this setup will give higher amps, not lower. You cannot use the motor’s “rated watts” to calculate amps, that value is pretty meaningless and is more marketing than reality. The amp draw is based on the load (prop) and how the boat is set up and driven, not on theoretical math based on fake facts. The Kv x volts again gives a theoretical rpm without load, under load the rpm will decrease.

That motor on 2S should draw around 20-40 amps if correctly propped. It is a small cheap motor and won’t handle more without damage.