Does level shifter have a maximum speed?
That is the limitation of FET level shifters. It is not the correct tool for the task you need to do.
Few meters of wire would have enough capacitance to slow down the rising edges, and the sharpness is also defined by the resistance value pulling the voltage up.
They are good for only low speed applications, and they are the right tool for bi-directional open-collector communications like I2C buses.
You simply need a push-pull logic level buffer, that can take in a 3.3V CMOS level signal, and output a 5V CMOS level signal.