Problems with the height adjustment

Hello everyone,

I have a problem that the router loses its height setting,
after leveling the Z axis.

In not so sure im clearly understanding the issue.

The spindle is carving a different depth at a different location on the wadteboard?
If yes, the solution is to surface the wasteboard using the cnc and to use equal thickness workpiece (and you might need more clamps so it doesnt lift bear that front corner)

Under the cut settings do you have ramp selected?
If so select vertical