Hi, I have a V50 t5 from 2004. There are 3 holes on the muffler where they are leaking exhaust gas, especially after long drives. When I start the car, the exhaust gas is coming from the end pipes as usual and the muffler seems to be tight but when I drive a longer distance I see that smoke coming out of these 3 holes. I have searched online and seen other pictures of the same muffler and the holes also exists on them as well, my muffler is dirty but definitely not rusty, not what I can see from the outside anyway and there are no strange noises, the car is quiet and sounds as usual. I am now wondering if there is some exhaust gas leakage and the muffler needs to be repaired / replaced or if it is normal for exhaust gas to come out of these holes when the muffler is kind of hot or any condensation water is released. I have attached some pictures where you can see where those holes are.
Any suggestion of what that might be?

Thanks in advance.