4 layers PCB mixed signal GND review
Zone 1:
The vias are tied together with traces, it might minimise high frequency inductance, for most designs it won't matter (less than nH equals GHz freq response). They are tied to the ground plane anyway if the stack up you have shown in the question is right, then there should be a global ground that is usually not visible in altium.
Zone 2:
Ground plane on the top layer, also won't do much because it would reduce the impedance to the ground plane to air by less than 1pf
You may want to double check the dfm because there are some nets that appear disconnected (there are no thermal connections reliefs between C130 U2 C143 C81 ect and thier associated power planes)