How to clean up DC power from interference really well? (better than RC)
Low Pass Filters need three structures

a series element (could be inductor, or FerriteBead, or Resistor); the resistor has DC_voltage drop

a shunt element (various capacitors, with ZERO ESR and ESL if possible; X2Y.com capacitors have FOUR terminals with internal charge_flow paths that minimize the &quot;inductively&quot; stored energy)

a well_controlled GROUND plane (copper sheet)


and need WELL SEPARATED return paths (ground connections) to input energy and output energy; you do not want to share VIAS between input and output Ground wires.
Be aware that PCB Vias have about 1 nanoHenry inductance.
At 100MHz, each via has 0.63 ohms reactance.
And why use a sheet of foil (ground plane) on which to build a successful Low Pass Filter?
Because WIRES are about 1 nanoHenry inductance per millimeter of length.
Use a plane.