Taking your 2020 Daikin inverter installation by authorized dealer first. Obviously, the quality and attention to detail by the dealer can be questioned. It is hard to accept that the compressor, condenser or evaporator leaked due to a manufacturing fault. There are higher chances of the leak to be in the copper tubing or the flare joints/O-rings made by the dealer techs. Unfortunately the concept of using leak dye has yet not caught up in our country. This makes tracing minute leaks impossible. Our method of finding leaks is to use Surf in water and a brush to apply the soapy solution.
Now coming to the vacuuming of the system. It is done to remove moisture from the system. If vacuuming is not done, then, moisture will freeze in the system and cause the a/c to choke usually at the expansion valve. Also if a certain amount of volume in the ac system is occupied by moisture, then the system will not accept a full charge of refrigerant hence, not provide the required cooling. So we can say that event though the care was taken to vacuum the system and filled to the correct level of refrigerant, it doesn't take into account slopy installation of the unit.
On a different note, the apartment I bought in 2006 still has the same refrigerant filled in Orient split a/cs I fitted in 2006 (all 7 of them) till date 
