Where do we place a Pi filter?
You are exceeding the maximum recommended supply voltage for the TPS2590 (20 volts) and that means the data sheet information cannot be relied upon. You are also within 1 volt of exceeding the maximum operating voltage. Not a good choice for 24 volts. It would be OK for a 12 volt power supply I reckon: -

The addition of an LC circuit (i.e. a resonant low pass filter) can make this especially worse: when switching the load on then off the current through the inductor that feeds the switch and load is interrupted by said load switch and, this can nearly double the peak voltage seen at the input to the load switch. Been there but never again!
Realistically, I wouldn't expect the load switch to survive. Mine didn't so I dumped the pi filter.