The buoyant force is greater than gravity, so it rises at an accelerated rate (air resistance is not taken into account)
The hot air balloon rises at an accelerated rate constant and the buoyant force is equal to gravity (air resistance is not taken into account). If air resistance is calculated, then the hot air balloon rising at constant speed is buoyancy = gravity + resistance
The object at rest or moving in a straight line at constant speed must be affected by forced balancing. When an unbalanced force acts on an object, the object must accelerate