The foxalian 4040 did he carving. It looks like the X plain is not square with the Y plain.
Wayne, FoxAlien sells a number of machines under the header of 4040. Likely loosening the Spoinboard and the frame connections in the corners and then pulling into equal diagonal measurements before re-tightening will resolve your issue, however you will get the most accurate information within the FoxAlien Facebook group found Here: FoxAlien CNC Router & Laser Machine Group | Facebook
@WayneThtasher here is a playlist on the FOXAlien machines. Included is a complete setup. https://youtube.com/playlist?list=PLWUBjmT-017Bkhu0AK2nH8PpdzkwHsdx3