it's just artifacs display for speedify the Moi's render! ;)

If you render your file you will see that all i good!

here your file saved in format Iges then rendered inside the very easy free simlab composer lite! ;)
(max 192 * 800) or 1920 *1040 in previous version 9
https://www.simlab-soft.com/3d-products/simlab-composer-lite.aspx
https://www.simlab-soft.com/3d-products/simlab-composer-old-download.aspx

Object are inclined for see the difference between plane and them! ;)
(and avoid the Z fighting effect)