If the system was serviced within the last month or so, this is not an uncommon issue. Water filters are very much like pumice stones. There are literally millions of little air pockets in each filter when it is first installed. Water has to gradually push all of the air out of the filters. And because the little pockets are so small, it comes out looking like a grey mist. This mist can cloud the glass when poured and can swirl and sit on top of the water or cling to the sides of a glass. The solution is to drain more water from the system - but it’s often not a question of a given amount. It is a combination of time and flow while the air pockets generally get “soaked” out of the filters. Sometimes this can last up to a month.
It does happen periodically that you get air in the water consistently. This can happen even if you may have had many years of using the same system without this issue. This tends to be worse in the first glass or two than subsequent glasses. This can be due to small changes in municipal water pressure to the home, that a technician changed the diametre of the piping to help the overall performance, that you have changed the frequency that you use the system, that there have been temperature changes in the installation location, different bends in the pipe to and from the system or that you got a filter from a batch with different pore characteristics - not a bad filter - just one that is slightly different.
A quick test to see if this is actually your issue is to pour a glass of water and sit it on the counter. Then walk away for 5 minutes or so. What should happen is that this air will float to the surface or cling to the side of the glass. It is important to recognize that this is just air and that it is harmless. The water is perfect for drinking. If any particulate actually sinks to the bottom then we should send a technician by your home to have a look and solve the issue.