What could make this situation become hazardous?

In this situation, both oncoming traffic and the red car overtaking you could create a hazard. Oncoming vehicles are always a potential risk on narrow or two-lane rural roads, especially while another car is overtaking, since the space for maneuvering is limited. The red car poses a risk because during the overtaking process, there might be insufficient distance, incorrect judgment of speed, or unexpected actions that could lead to a collision with oncoming traffic or your own vehicle. The tractor was not a direct hazard in this specific moment, as it was stationary and off the road, but always stay alert for possible movement from agricultural vehicles, especially when warning signs are present. Remember, when being overtaken, maintain your speed and lane to ensure a predictable environment for all drivers, and always scan ahead for oncoming vehicles or other hazards.