Sen2Cor and L2A products

I have downloaded L2A atmospherically corrected data. I wanted to create a cloud mask using the 60m aerosol band and Cloud contamination confidence band. The Cloud confidence band does not have 1 to 100 values; it has unusually high values and does not represent the cloud mask at all.

I have in the past created cloud masks using these 60m bands but with data processed in house using Sen2Cor. I ran Sen2Cor on the same scene and it produced a reasonable 1 to 100 values cloud confidence map.

Do I need to process the data with Sen2Cor to get the correct output??