No one likes to lose money. In a home with forced air, losing air equals losing money, so it is very important that the system is sealed up tight. This is not always easy though, since leaks can be hard to detect.
A common failure point for your HVAC system is near the HVAC unit itself, since you will have higher pressure there. This does however not mean that the issue can’t pop up anywhere else. If you notice that your system isn’t working as well as it used to, or if there are strange smells and dust coming out of the vents in the home, you might have a leak into an area of your home where it picks up those things and brings them into your living space instead. It is possible to find leaks using thermal imaging, so that is a good tool to have at hand when looking for issues.