AW3225QF, 10 bits HDR calibration incorrect max luminance

I recently bought my AW3225QF monitor and I noticed that when the monitor is in 10-bit mode, the maximum luminance it can reach is 1010 nits, but Windows reports that its maximum is 993 nits. I thought it was normal, however, when I change the color depth to 12bit or 8bit, the maximum luminance when calibrating clips between 980 and 990, which I think is more accurate, is this expected? Is FRC affecting the tone map?