How big of an issue is this?
Just think about the fluid dynamics of what is going on here. The pressurized gas in the barrel, between the time the bullet passes the gas port and when it leaves the muzzle, is taking the path of least resistance. It goes up through the gas port in the barrel. Some gas may find it's way out between the gas block and barrel (even if alignment is perfect). The gas goes through the gas block and into the gas tube. Some gas finds it's way out between the gas block and the gas tube. Enough gas (hopefully) travels down the tube and hits the carrier key, providing the force to cycle the rifle.
Neither the mechanical fastening of a gas block to a barrel or the gas tube to the gas block provides a complete seal. If it could, plumbers would use roll pins and set screws (haha).
There is very little control over the leakage between the gas tube and the gas block. Tubes that have to be jammed into place to align the roll pin **probably** leak less. Looser fitting ones **probably** leak more.
The gas leakage between the barrel and the gas block may be able to be reduced IF the port on the gas block isn't fully aligned with the port on the barrel. The gas block port is bigger than the port on the barrel, so you typically have some slop to work with. In this case, the rifle cycles correctly, so no corrective action is required. However, if the rifle was short stroking, the first place to look is the alignment and attachment of the gas block. I have had a gas block that was set screwed without dimples drilled in the barrel come loose no matter how tight the screws were tightened or how much loctite went on those screws. It got replaced with a clamp on style block. No issues after that.
Additionally, aluminum gas blocks eventually leak (and wear out) quicker since the gas port gets enlarged faster simply due to the materials involved. It is still a lifespan in the thousands of rounds.
Final thought - it's easier to see the leakage on a stainless barrel due to the color difference. Matte black carbon leakage is harder to see on a matte black barrel.