What is the disadvantage for can annular type combustion chamber?

The main disadvantage associated with can-annular combustors is the limited cooling effect of the dilution air. Since it is located in the center, the dilution air is exposed to reduced flow velocity and can't absorb the excessive heat as efficiently as in other combustion chamber types. This phenomenon leads to a less uniform distribution of temperature across the combustor and increased thermal stress on the components in the center of the combustor.