Overlapping GND and PGND on different layers of a PCB
Realize that each ground has some small resistance and inductance ~5 nH/cm that may not seem like much, but then some circuits may want to be high SNR or isolation on the order of 40~60 dB or more.
Each layer will have some capacitance that will couple crosstalk if dV/dt exists from current surges to high impedance inputs.
Without going thru a signal analysis, you might be lucky or not. Do you feel lucky? If not examine the effects of high impedance inputs if a surge step load runs under it. Use Saturn PCB Design.exe to estimate your capacitance, (ballpark) based on overlap area and gap with some tbd mV rise in ground voltage.
Mutual inductance works on current for low impedance inputs and outputs.
The wandering gaps have a smaller capacitance but some, due to the electrode cross-sectional area of copper thickness.
Consider f-3dB=0.35/tr for your upper frequency ( ignoring harmonics) from some L/R or RC rise time =Tau , not exact but close enuf.