Why does an .2mm initial layer measure .4mm +?

most definitely .2

this is the start of the skirt

;Start GCode end
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
; Filament gcode
;LAYER_CHANGE
;Z:0.2
;HEIGHT:0.2
G1 E-1.00000 F3900.000
G92 E0
G1 Z0.200 F9000.000
G1 X159.072 Y274.581
G1 E1.00000 F2400.000
;TYPE:Skirt
;WIDTH:0.42
G1 F900.000
G1 X160.348 Y275.020 E1.04230
G1 X161.496 Y275.728 E1.08461
G1 X162.463 Y276.669 E1.12691

this is the start of the object preimter

;TYPE:Perimeter
G1 F900.000
G1 X157.044 Y292.151 E1.34171
G1 X161.575 Y292.149 E1.48378

start of object external perimiter

;TYPE:External perimeter
G1 F900.000
G1 X162.161 Y291.772 E1.14862
G1 X157.425 Y302.181 E1.50717
G1 X157.431 Y315.364 E1.92053

start of the infill

;TYPE:Solid infill
;WIDTH:0.420472
G1 F900.000
G1 X156.757 Y281.961 E1.02619
G1 X156.757 Y282.495 E1.04296

there is no change in z height until we get to gcode end

not only is the object 0.4m high, extrusion is shit, here are many i have printed (not all in the same location) - i have tried changing just about everything (nozzle temp from 180 to 240, bed temps, recalibration, lowering z offset, trying 0.4mm size object and 0.4mm extrusion height.

Note this is absolutely related to the xy coords of the object on the bed and is IDENTICAL on a glass surface, the snapmaker stock surface & and an energetic PEI smooth plate too. aka this thread (thanks to @Artezio for all his help, and just plain listening to my crazy!) io should note the 'good squares in the 5x5 matrix are ~0.22mm - aka what I would expect.

i cut the model to be just the top center square to speed up testing iterations.

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