Due to a problem in the Intel® Quartus® Prime Pro Edition Software version 23.2 and earlier, you might see that the number of M20K's reported in the Fitter Resource Usage Summary is less than the number used in the final placement.
When differences occur, it is the number that is used in the final placement that is correct.
This problem can occur for designs that contain M20K instances that utilize byte enables.
This problem is scheduled to be fixed in a future release of the Intel® Quartus® Prime Pro Edition Software in which the Fitter Resource Usage Summary will correctly factor in the M20K byte enable usage.