Calculating shrink and distortion - Anycubic Photon Mono

[thrasher7811]

I create a 2in disk, .25in thick to calculate the shrink percentage of my resins. However, it reveled another issue. After printing the disk, I found that the side that printed first, was much thicker than the side that printed last. Does anyone know why this happened or how to correct it? My first thought was orientation but I figured I would ask the community. Thanks in advance for the help.