PCB designing with Autodesk Fusion 360

Yes, one reason for spread ground might be that I am using many GPIO pins and routing them to Pin header. I have looked at nRF54L15 reference layout and the components that I have places are mostly similar to that reference layout. Also, the chip is 6×6 mm only and many components such as clock, caps, etc are arround so less space. 

Design rules I have checked, and they are ok. With could of violations but they are at safe distance hence no problem, Still I am figuring out the antenna layout part. and hopefully that too be shorted out soon! I got some feedback from the manufacturer but still need to correct those parts.

The free version does not have four-layer support.

Also, I have changed the antenna after I got the feedback now, I place the antenna at the center of the edge of the PCB to have equal ground plane on both the sides. 

One thing about spread GND layer is to place VIAs on GND islands to have same ground signal at the same time at all places on the PCB.