Uneven print at one corner of the build plate

[D0dde]

Machine: Brand new Creality CR-M4

Slicer: Creality Print (Cura fork)

Machine setup: Standard out-of-the-box-configuration. Placed on a stabilized table with a draft shelter around it

Symptoms: Very rough print quality always in the same one corner of the build plate where the print also semi-detaches during printing operations.

What have I tried: Dont know what to try. The machine has auto leveling so no screws to adjust beneath the build plate and the proper nozzle and build plate temperatures are being used with the generic white PLA test filament that came in the box with the printer.

I have absolutely no clue whats causing this. The results are consistent between prints of the same model, which is a mirror mask for a telescope mirror, basically a ring with a 3 cm brim and is quite big. The print stretches almost all the way out to the edges of the build plate with is 450x450 mm. Three quadrants of the build plate prints perfectly fine with proper adhesion and nice smooth surface and details but in the last quadrant everything seem to get turned on its head.

Please view this shared bed leveling graph on plotly. It s made with the Bed Leveling Visualizer from within OctoPrint. To my untrained eye, this bed looks crooked. Someone said they used aluminium foil under the build plate to prop up uneven areas but really?

https://plotly.com/~D0dde/1/

Please assist if you can.

[Bikeracer2020]

Someone said they used aluminium foil under the build plate to prop up uneven areas but really?

Please assist if you can.

Yes, really!
You can buy it in adhesive backed rolls a few microns thick.

A printed bed levelling test of which there are many might give you an idea of just how much the bed is quite probably warped.