RLC impedance ratios are critical to understand for load/source Attenuation of Stray E or H fields and conduction current attenuation. Every part has conduction resistance. Even groundwires have ESR + ESL.
Impedance is a function of risetime which is ~1/3 f for reactive components or stray coupling of E (v) or H (i) fields.
Choose 100mV current shunt to test for current and conduction noise, e.g. ESR ripple in caps
Next time put detailed schematic and layout photo in question, so we dont have to guess or use crystal ball.