Yeah, it is a very tight time window where you can get through. You basically had to move as low as possible and dash into it while the water is still flowing down so that you get to it right as the animation resets.
It took me like 15 tries out of which I got it in 4. I then died at the easiest part 3 times haha.
The end screen was the little guy sitting on the ground and telling me to get through with less deaths, so I think that I made it?