Too many vias on ground trace
We are clear now that it is microcontroller with two crystal-based clock circuits attached to it. My guess is that signal layer below the top one is ground, and these vias connect the red tracks around the crystals to that layer, I guess "to make better ground". But that may not be the best solution in such circuits.

As I said in the comment to the questions the best is to ask developer of the board the following questions:


Why did not he consider putting bigger ground polygons at th top layer as it is clear that there're no components around the crystal circuitry?
Did he simulate the circuit and perform impedance/EMI check as the generating components are relatively close to each other?
Did he consider the negative effects by putting vias creating ground loops?


And finally, there must be a clock generation circuit layout guideline in the datasheet or application note of the STM32 microcontroller, which should be followed as much as possible given design contraints.

Update: I asked my friend who specializes on the stuff, and his feedback was that actual layout would depend on the frequency, and that ground polygon (instead of separate tracks at the top) would do better job in shielding.