In the new v1.11 firmware released today, Sony seems to have fixed these problems. While they addressed a major issue related to monitoring in the last firmware, this particular update is fixing a smaller problem that's related to the implementation of the XAVC codec. Instances of both macro blocking and tearing were cropping up, and the engineers over at Sony have managed to erase the problems by slightly modifying how the codec was responding with their image processing. 

cinema5D recently posted this video showing the improvements:

The only thing listed in their notes on this firmware is this:

1.) Image quality improvement regarding XAVC recording.

Obviously we know it's a little more complicated than the basic sentence above, but thankfully we've got video proof to show us exactly what the issue was, and how it's been addressed. This camera has a few quirks, but as a more budget cinema camera solution, it ticks off a lot of boxes, so hopefully Sony can continue to improve it with firmware updates. 

To download v1.11, head on over to the links below. 

FS5 Firmware V1.11 — Sony US

FS5 Firmware V1.11 — Sony UK