What is "charge dumping"?
They &quot;smooth&quot; voltage transients, but they do act also like low pass filter among with already present R2,R3,C2. Now you add a LPF with R2-C4 and R3-C3. These two filter have to be identical, the resistors and C3,C4 need to have small tolerance.
The main purpose is to limit dv/dt on the inputs of the amplifier.
EDIT:
Common mode noise in differential probe: EEvblog showing signal artefact of square pulse due to gain/filter mismatch of positive VS. negative signal.