Insignia Low Brake Fluid Soft Pedal

A consistently low brake fluid level accompanied by a soft brake pedal definitely warrants investigation. Since you've already checked the master cylinder and brake lines for visible leaks, the next most probable cause could be worn brake pads or discs. As they wear down, the pistons in the calipers have to extend further to maintain contact, which in turn requires more brake fluid from the reservoir. This would explain the drop in fluid level and the altered pedal feel. When was the last time you had your brakes inspected? Also, is the brake warning light constantly on, or does it come and go?

I haven't had a proper brake inspection in quite some time, probably over a year. So, if worn brakes are the culprit, should I be concerned about any potential damage to other components, and is it safe to continue driving the vehicle in its current condition? Is there anything I can check myself before taking it to a mechanic?

Given that it's been over a year since your last brake inspection, it's highly probable that worn brakes are contributing to the problem. Driving with low brake fluid and questionable pedal feel can be risky. If the fluid gets too low, you could introduce air into the system, leading to significantly reduced braking performance, or even complete brake failure in a worst-case scenario. While you can visually check the thickness of the brake pads through the wheel spokes, it's best to have a professional mechanic inspect the entire system, including the discs, calipers, and brake lines, for any signs of wear, damage, or leaks. They can also properly bleed the brakes if necessary. Continuing to drive without a thorough inspection and potential repairs would not be advisable.

I appreciate your detailed advice. It seems the best course of action is to take the car to a workshop for a comprehensive brake inspection. You have clarified a lot of the issues for me. As it turns out, it was indeed worn brakes, the bill came to 480€ and it's all fixed now.